Which words may start with “al-”?
The word alright comes from "all right". Where did the second l go?
Similarly: altogether from "all together".
The link below gives the history of this spelling:
As to why this change is taking place, it isn't easy to give an answer. Perhaps its followers have decided that it should imitate the word "fulfil", where the double consonants were done away with when the two words full and fill were united.