I have a situation where I have a child table that will be a child to two different parent tables. It's kind of like this:

PARENT 1     PARENT 2
pkParent1    pkParent2
   |            |
   --------------
          |
        CHILD
        pkChild
        fkParent1
        fkParent2

My question is...Is this good design? Is it commly acceptable to have a child with two foreign keys pointing to differnt parent tables when one or the other fk value will be null?