Ok gave up on MKVToolNix and now trying Divx Plus Converter but now I have a new problem...

I have 2 different MKV's which i know for a fact are identical in every way,frame rate, aspect ratio ect.. ect... but for some reason it wont let me join them.
Every time i click combine all videos into one file the 2nd file has a ! next to it and when i click on it it says
this video will not be inclded in your final video because all files in combine mode must have the same resolution, frame rate,sample rate, bit-depth and channel count as the first file listed. BUT THEY ARE! ???