Technically speaking, yes, you can sell your NFT on different marketplaces. But it’s not the best idea and will certainly ruin your reputation. Collectors will not buy from you again if they find out (which they will) that you’re selling the same art piece across various marketplaces, especially if you sell the same NFT for a different price on another NFT platform. 

In terms of sales, it is also better to mix things up and offer different NFTs on different marketplaces rather than trying to sell the same creations on all your various accounts. By offering different NFTs on several marketplaces, you can appeal to a wider audience of buyers who may like one of your pieces more on another platform. You can also curate the collections or artworks that you sell on each platform so that they follow a specific theme.