Origin will not accept my Spore Steam CD Key

I got spore on steam and I wanted to make a spore account, someone told me that I should try using Origin to do that, so I did, it asked for a product key so I used my Spore CD key from steam, and weirdly enough it recognized the code. 2*******************9

Did it not accept it because I already used it on steam?

I saw online that it didn't matter if I had it on steam already, so I am a bit confused.

???