Name: Sandy B. Ford River Twp, Michigan UP (Zone 4b) (Zone 4b-maybe 5a)
I think it would be quite unusual for a butternut squash (C. moschata) to cross with a zucchini (C. pepo)... but I have no other explanation for what might be going on with your seeds and plants
“Think occasionally of the suffering of which you spare yourself the sight." ~ Albert Schweitzer C/F temp conversion