The anemone would end up being 50% of it's original size. Keep in mind though that size is relative to the amount of water they are holding at a given time, not tissue mass so it can be a bit deceiving.
Since it has been two weeks since the onset of the odd behavior the two would have healed up and looked no different than before it happened. I find it odd though that you would not have noticed it if the anemone was out in the open. Where did you get the rock from and if an LFS
did they have BTA's at the time?
Do you spend long time periods away from home? When they split it can take 12-24 hrs (sometimes less) and will not normally leave the general area right away if at all.