So i am a bit new to the game and see in builds idea where people say use a plus 2 tome for int at this level and plus 3 at this level

my question is can you take more then 1 tomb in the same stat? i assume if the answer yes that they do not stack and if you take a plus 2 at level 7 and a plus 3 at 11 ( i am making up those levels) you will only have a total of +3 to that stat. Or when you use a tomb on a stat can you not use another tomb on that same stat again?

Thank you