Whippit

Today i run off a banner which need to be joined up the middle it was to be 3800mm x 2600mm The files were created and sent from Sign Lab as two septate images (3800mm x 1310mm) They were showing as the correct size in versa works but when they printed one came out 3700 x 1310 and the other 3740 x 1310?? Both to short and different sizes??? The media was HQ banner, a brand new 50m roll. Anyone have any ideas what has caused this before i try to reprint them tomorrow.