Phol and Balder

Second Merseburg charm:

Phol ende uuodan uuorun zi holza
du uuart demo balderes uolon sin uuoz birenkit
thu biguol en sinhtgunt. sunna era suister
thu biguol en friia uolla era suister
thu biguol en uuodan so he uuola conda
sose benrenki sose bluotrenki.
sose lidi renki
ben zi bena bluot zi bluoda
lid zi geliden sose gelimida sin.

Everyone agrees that Phol and Balder is the same person.
Is it possible that they are old nom. and gen. stems respectively (in
which case Phol would have lost a -d- or -d- in Balder inserted in
-dr-? Old Norse does have some masculines ending in -ar in the
genitive. Is this the case for OHG too?

'balderes' doesn't seem right in the meter either.

And yes, I have noticed the initial ph- vs. b-. That would translate
into PIE p- vs bh-, a Noreen alternation.

Torsten