There's a difference between "Anubis"(the mantle) and Anubis(the person holding the mantle). In this case, you'd be "Anubis", as is your right as the holder of the Anubis mantle. You'd also have the (unnamed) mantle of Anubis, who's just a really powerful spirit who gave away his old mantle. To put it in a clearer way:

Alice is Anubis. She has the mantle of Anubis. Alice gives her mantle to Bob.

Alice(no mantle), Bob(Anubis)

Now Alice's mantle regrows. She has a mantle called the Mantle of Alice. NOT the Mantle of Anubis, since she's not Anubis any more.

Alice(MoA), Bob(Anubis)

Then Alice dies and Bob recovers her mantle.

Bob(Anubis, MoA)

So Bob doesn't really have two mantles of Anubis, he has a mantle of Anubis and a Mantle of Alice. 


EDIT: It's also of some note that the Mantle of Anubis and the Mantle of Alice are pretty similar, since Alice, the unique person, imprinted her unique identity on both of them. So, like JS said, it's pretty pointless for Bob to collect her mantles unless he has a personal obsession with Alice.