In Adobe Premiere Pro, you can edit audio, add effects to it, and mix as many tracks of audio in a sequence as your computer system can handle. Tracks can contain mono or 5.1 surround channels.
In addition, there are standard tracks and adaptive tracks. The Standard audio track can cope with both mono and stereo in the same track. That is, if you set your audio track to Standard, you can use footage with different types of audio tracks on the same audio track.
You can choose different kinds of tracks for different kinds of media. For example, you could choose for mono clips to be edited only onto mono tracks. You can choose for multichannel mono audio be directed to an Adaptive track by default. Read more at Adobe.