ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh Why Not?
Cross pollination may or may not occur, (you can't see it) and it has no effect on that generation (or season) of plants.
You will not get hot bell peppers, or mild jalapenos.
If cross pollination has occurred, the seeds from those perfectly normal banana peppers will most likely produce some unstable cross.
Meaning a sickly plant with mutated peppers. (in my experience)
If those plants were readilly available, and that is all you want to grow, buy the same plants next year.
If you want something you can't buy locally as a plant (7 POTS are nice
), then buy seeds from a reputable source.
Good Luck!