Hi T-Lady,
The Uncle Bob has very wide selection (it is in German but has english translations), you could also go for Baker Creek too:
Baker Creek Heirloom Seeds - 1200 Heirloom Garden Seeds in our Heritage Seed Catalog, Historic Gardening Shows and Plant Festivals
Or Vreken (but this one is in Dutch) :
https://www.vreeken.nl/2007/index128...hp?urloptions=
I have ordered from all 3 seeds company before and they are reliable.
You can grow more than 1 same species squash but to save seeds, you will have to hand pollinate them
. Good luck with your squash hunting ... it is addicting isn't it
.