GPL question

[Nicholas R. Markham]

I have a program that I'd like to utilize the GNU Scientific Library.
Since the GSL is distributed under the GPL (not the LGPL), this means I
would have to distribute my program under the GPL as well.  I have no
problem with this per se; however, the program in question is part of a
larger package, which contains other programs I don't want to distribute
under the GPL.  (In fact, since I don't personally own the package, I
couldn't GPL it even if I wanted to.)

I'm considering some sort of hybrid approach, where the program in
question is distributed in two ways: on its own, under the GPL; and in the
package, under a different license.  Would something like this be legal?
It seems to me that it should, since there is no single program that uses
the GSL but is not distributed under the GPL.