As black_zion already said, no is the answer. Crossfire has always required the cards be of the same type as each other. They can be of different clock speeds and memory amounts and both will then operate to the lower common denominator.
Very few games support crossfire and even the ones on the supported list may or may not be working well in current drivers. Crossfire is deprecated after DX 11. It will not exist moving forward. It is replaced by Multi GPU in DX 12 but in general DX 12 support isn't that dominant yet and Multi-GPU support is almost non-existent. Less than 3% of gamer's utilize crossfire so unless you have a specific game you know it works well with and you focus on that game or few games it works with it is rarely worth messing with. It is always best if possible to have a single card solution that meets your needs if possible. Just adding a second card can add a lot of issues to games you would not normally have issues with. Most games that are or were crossfire compatible operate at very acceptable frame rates on current mid and low level cards. This is the crossfire compatibility list of games that do or ever did support it:
Crossfire Game Compatibility List | AMD Crossfire Wikia | FANDOM powered by Wikia
