It depends on who fights who,
if ROTS Anakin fights AOTC Anakin and ROTS Kenobi fights AOTC Kenob- ROTS Anakin kills AOTC Anakin quicker then ROTS Kenobi himself from AOTC. Then he teams up with AOTC Kenobi(he can do it alone) and they kill ROTS Kenobi.
If ROTS Anakin fights ROTS Kenobi and AOTC Anakin fights AOTC Kenobi, then AOTC Kenobi defeats AOTC Anakin first, because Anakin by this stage is very reckless and makes allot of mistakes and he teams up with ROTS Kenobi, to take ROTS Anakin.