Planar Binding Scroll CL Duration Issue

[Ewe]

Planar Binding Scroll sold at Thayan in BG seems to behave incorrectly in relation to its duration. It is most noticeable on level one characters.

Steps to reproduce:

1. Make neutral level 1 Wizard (no conjuration focus feats were taken).
2. Make neutral level 1 Bard.

3. Wizard uses scroll Planar Binding (chooses Efreeti).
4. Bard uses scroll Planar Binding (chooses Efreeti).

The Bard's Efreeti lasts approximately 11 minutes (as advertised given the CL of scroll is 11 and it states 60seconds per CL).

The Wizard's Efreeti lasts approximately 2 minutes (maybe less? but definitely far less than the bard's).

Hypothesis: The Planar Binding spell when used by a scroll may be using the Wizard's actual CL rather than the scroll's CL? Though, not in case of bard? If so, does this mean a level 30 wizard would have a 30 minute planar from scroll?

I had to RCR my wiz to bard in order to use this scroll to level... very frustrating.