I maintain a software, a small PHP library, that is released under the LGPL version 3 license (LGPLv3). Someone wants to use the library in their software which has the GPL version 2 license. This license compatibility matrix suggests this is not possible without changing the licensing terms of one of the software. I have been requested to dual-license my code under LGPLv2.1 and LGPLv3. Does it make sense, and what might the drawbacks be?