These are known as tautologies or tautologous expressions.

These are known as tautologies or tautologous expressions.

Some examples from the Guardian Style Guide:

Aum Shinrikyo
means Supreme Truth sect, but note that the "aum" means sect, so to talk about the "Aum sect" or "Aum cult" is tautologous

affidavit
a written declaration made on oath, so "sworn affidavit" is tautologous.

Eid al-Adha
(Festival of Sacrifice) Muslim festival laid down in Islamic law, celebrates the end of the hajj. Note that eid means festival, so it is tautologous to describe it as the “Eid festival

gambit
an opening strategy that involves some sacrifice or concession; so to talk of an opening gambit is tautologous — an opening ploy might be better

regalia
plural, of royalty; “royal regalia” is tautologous

As a side note, tautologies are often found in place names, my favourite is The La Brea Tar Pits, meaning The The Tar Tar Pits.