As
@Joe123 said, Afternic, Sedo, DAN, and the other general marketplaces don't have exclusivity restrictions. You can list your domains on as many as you like, and you can use whichever nameservers you prefer.
The brandable marketplaces typically have some restrictions:
A.) SquadHelp: SH has different domain listing / ownership types, and their restrictions vary accordingly.
- If it's a standard domain, you're allowed to list it any and everywhere you want.
- If it's a seller-owned premium domain, SH automatically syncs it to Sedo and allows you to list it at Afternic (at a higher price, minimum markup of 8-10%). You'll have to handle the Afternic listing yourself. And if the domain sells at Afternic, you'll have to pay SH the difference between Afternic's commission rate and theirs. The difference (in percentage) will be applied to the domain's price at SH, not its higher Afternic price.
- If it's a SquadHelp-registered premium domain, SH syncs it to Sedo and also lists the domain at Afternic by itself.
B.) BrandBucket: I no longer have domains at BB. But, from what I remember, BB requires full exclusivity. They sync domains to Sedo and DAN by themselves.
C.) BrandPa: Only ever had 1 domain at BrandPa. They require you to use their nameservers (just as the other brandable venues do), but I don't think they had/have any exclusive listing restrictions.
N.B: These marketplaces can change their restrictions and requirements at any time. If you're interested in using them, be sure to get in touch with their support for up-to-date info.
Hope this helps.