On the stock coil that comes with the T2 on the top and the bottom of the coil covers are a 1/2'' round mark in the plastic !! those are not the plastic mould holes those are infact the pinpointing marks on the coil,regarding after market coils then of course they dont have those pinpointing marks,so the best way if using a fter market coil in just put a few coin targets down on the ground and see how they respond in regarding the position of the target under the coil and take a mental not.Not alot else too suggest on that one,pinpointing is usually spot on excuse the pun.
Regarding the pinpointing,alot of pinpointers work on a similar freq to the detector and can 'crosstalk' as its called,its nothing wrong as such its just both electrical signals crosstalk and nothing wrong with the detector or probe,you may try keeping the detector slightly on one side away from the probe and that may reduce the problem,or another possible solution might be try changing the freq shift and try one of the other freq either higher or lower and that may reduce the problem,but the shift in freq is only very small but may do the trick.
Its not unique with the T2 either,my Deus and Garrett probe cross talk as well,my suggestions may or may not help,but you are not alone for sure.