The usual IANAL applies.
Yes, according to http://www.gnu.org/licenses/license-list.html both of these licenses are compatible with the GPL, so based on that it is possible to incorporate code using them in a GPL project.
See http://www.gnu.org/licenses/gpl-faq.html#WhatDoesCompatMean for the explicit declaration of that possibility:
It means that the other license and the GNU GPL are compatible; you can combine code released under the other license with code released under the GNU GPL in one larger program.
The practicalities of this are interesting. The next bit is just opinion, but I personally wouldn't feel comfortable making something in the order of a one-line or two-line change to an otherwise GPL function, and declaring that one-line or two-line change to be under another license. On the other hand, if I could split all of my code changes/additions off to a separate module, then I'd feel more comfortable with being able to license that separate module differently.
There are real-world examples of this kind of release. E.g. in id Software's Quake III Arena source code release, the entire release is - of course - a GPL release, but certain modules are released under other licenses.
Here's tr_animation.c (GPL): https://github.com/id-Software/Quake-III-Arena/blob/master/code/renderer/tr_animation.c
And here's md4.c (RSA): https://github.com/id-Software/Quake-III-Arena/blob/master/code/qcommon/md4.c
It's worth reading the readme to see how the overall licensing of these items was handled: https://github.com/id-Software/Quake-III-Arena/blob/master/README.txt
And as always, consulting with a lawyer knowledgable about software licenses is utterly essential to ensure that you don't overstep the bounds of what you are permitted to do.