Unless you ar eplanning to save seeds it does not mater. Crosses only show up in the next generation. Pisum will cross but not readily, you will get a minimum of crossing even if you do save seeds. On the other hand with both growing on the same trellis, you will have to be on your toes to avoid avoid mixing them at harvest.

Thank you so much for your reply! I'm not planning on seed saving these, so I'll go ahead with my plan.