I know of 2 co-workers at work who are coming in late and leaving early should i report it to the manegar?

i work in a group home, and i know of two co-workers who are lying when they fill out their paperwork, a legal doent, that they are working certain hours when they are arriving late and leaving early, should i tell the manegar? one of them is my old fwb and enemy co-worker. i don,t want it to seem like i am bitter toward them, but they have been doing this for quite a while. manegar is not aware of my relationships with these co-workers.