In Mexican Spanish (not sure if other Spanish speaking countries use the word too) we call "tocayo" to those people that share the same name as us (but not necessarily the same last name i.e., Juan Gonzalez and Juan Carlos Castillo are tocayos).
I was wondering if an equivalent for this word exists at all in English or maybe even an expression?
People who share your name (whether full name or just part of it) are your namesakes:
A person or thing that has the same name as another
As Hot Licks points out in the comments, namesake is most commonly used for someone or something that is intentionally named after you, but it can be used for non-intentional, coincidental name identity as well. The Wikipedia article has a brief discussion about whether a namesake is necessarily named after its, erm, namesake—starting out with the following:
Namesake is a term used to characterize a person, place, thing, quality, action, state, or idea that has the same, or a similar, name to another—especially (but not exclusively) if the person or thing is actually named after, rather than merely sharing the name of another.
The OED article on namesake has quite a few citations using the word. In many of them, it’s quite hard to tell from the snippet whether the namesakeness is coincidental or intentional; but a few are definitely coincidental:
The Beacon … was nicknamed ‘the State Fair apple’ and was for years sold at its namesake event. (Minnesota Monthly, 1995)
I enclose a letter for your funny namesake and kinsman. (Croker Papers, 1826)
So even though it is most common to use the word for someone or something that is intentionally namesaked after someone or something else, it is legitimate and historically precedented to use it to refer to more coincidental namesakenesses, too.
Merriam-Webster's Eleventh Collegiate Dictionary (2011) seems to split the difference between the answers offered by Janus Bahs Jacquet and Nicole:
namesake n [prob. fr. name's sake] (1646) : one that has the same name as another; esp. one who is named after another or for whom another is named.
Thus, according to Merriam-Webster, the name can be coincidental (Janus Bahs Jacquet's contention) but more often indicates an intentional naming after (Nicole's contention). It's also interesting that a namesake can be the person who originally had the name or the person who is named after that earlier-born person.
In defense of Ishan Yadav's suggestion, I note that the Eleventh Collegiate offers this entry for homonym:
homonym n 1 a : HOMOPHONE b : HOMOGRAPH c : one of two or more words spelled and pronounced alike but different in meaning [example omitted] 2 : NAMESAKE 3 : a taxonomic designation rejected as invalid because the identical term has been used to designate another group of the same rank — compare SYNONYM
A third contender is eponym. Here is the Merriam-Webster definition:
eponym n 1 : one for whom or which something is or is believed to be named 2 : a name (as of a drug or a disease) based on or derived from an eponym.
It seems to me that eponym is the least satisfactory of the three choices because it explicitly entails being "named or believed to be named after another person"—not just sharing a name through happenstance. But namesake has a bias in favor of the same interpretation—at least in U.S. usage—as evidenced by the "esp. one who is named after another or for whom another is named" language in the MW definition. And homonym can mean simply "namesake," which would seem to transfer all of the benefits and liabilities of that word's definition.
Ultimately, the definitions of all three words tend toward definition 1 of eponym, but both namesake and homonym (definition 2) can be defended as not always referring to a particular other person as the source or recipient of one's name.
"Namesake" technically means anyone who has the same first name as you, but using it in that broader sense may cause confusion. The word is most commonly used to mean someone who not only has the same name as you, but someone whom you were named after or someone who was named after you. For example, if you were to say, "The Queen of England is my namesake," you might just be saying that you are named Elizabeth and so is the Queen of England, but most people would assume you meant that your parents deliberately named you after Queen Elizabeth.
A homonym is a word that is said or spelled the same way as another word but has a different meaning. "Write” and “right” is a good example of a pair of homonyms.
Homonym traces back to the Greek words homos, meaning “same,” and onuma, meaning “name.” So a homonym is sort of like two people who have the same name: called the same thing but different.
However, as answered by @Janus, namesake is a better word.
Note: This answer is perhaps ill-advised, but I felt it was too long for a comment.
As other answerers have stated, namesakes, answers your question. However, I would argue that the word namesakes would be unlikely to be used with the mood that you describe in the question. I certainly do not expect to hear anyone joyously exclaim that he and I are namesakes.
One thing to note is that, in some areas you might be able to get away with using tocayos, in place of an English equivalent.
As you say, the word, tocayos appears to be slang. I was unable to turn up a root for the word (or perhaps I was, but simply didn't notice, due to my poor Spanish).
I would imagine that there is a noun that at some point was conjugated, and perhaps adjusted a bit to be able to be conjugated, so as to create the word tocayos (I might be very far off, but it seems reasonable no?).
If you were so inclined as to manufacture an English word to fit your needs. It might not be unreasonable to take one of the many synonyms for name and adjust it similarly to try and fit your purpose.
For example the word sobriquet, defined as nickname, might fit such a purpose. You could perhaps then refer to yourself and your namesakes as sobriquetes, which I would pronounce as soh-bruh-ket-eyz. This pronunciation would then probably sound, to someone unaware of the root word, like an adjustment of bruh. Of course, this would probably need some explanation outside of context, but in context sounds, at least to me, much more wield-ly than the word namesakes.
