Rent checks from someone other than the tenant

BP,

Today was a first - I received a rent check with the name and address of someone I've never heard of. In the memo line, the name of my tenant was written along with the address of the rental property, and it was made out for the correct amount.

Do I need to know who this person is? Are there any tax or legal implications to cashing a check from someone I don't know, or that is not listed in the lease as a tenant?

Thanks,

Lance