Hello,
I cut the layouts a bit larger than necesary and than stick (with tape) one layout on a spare piece of PCB.
Align it in such a way that it is a stop for the PCB you want to make.
Turn it and align the second layout before taping it on to the spare PCB again. I use additional lines, on every corner of the PCB, in my layout, for alignment.
You got a sandwich like layout wherein between you can put your PCB. Then before exposure, also tape pieces of the layout to the newly to be exposed PCB. Now it is stable enough to turn it after the first exposure.
grtz
Simon