if I understand you correct, yes, 2-3 timing is out
When checking 1-4 you connect to cable/plug 1 or 4
when checking 2-3 you connect to cable/plug 2 or 3
Do it first for idle - F mark
Then check with 2500, you should see it ideally in the middle of double mark. If you have first set F at idle for both 1-4 and 2-3, then it must be the same for 2500 RPM for both, as this is managed by advancer (springs). It cannot be be different, unless there is some issue in strobe pickup in higher RPMs.