You may get more feeling out of the recording if you both play together, but I have done a lot of recording at home alone, and with another guitar player. The quality of the recording suffers if you record it all live. If you can record a performance, that's a great way to go. But if you're on a budget and you're using an old four track in your basement, you should do everything you can to keep the sound quality high. That requires recording the tracks individually. That works for me, anyway....