Quote I have a recorded audio interview from two microphones that are recorded as left and right tracks on an MP3 file. I would like to combine the two tracks into one and create a new audio file with the same combined audio on both left and right tracks. Thanks.

Easy Peasy. Place both MP3 clips on the timeline, select both and click Sync by Audio. Trim as needed, then produce as WAV:

Quote I have a recorded audio interview from two microphones that are recorded as left and right tracks on an MP3 file. I would like to combine the two tracks into one and create a new audio file with the same combined audio on both left and right tracks. Thanks.

One way to copy the audio from the L to R or the reverse can be used to have the same audio on the L + R (mono)
Can do with AudioDirector ... see the video
After, in the timeline adjust volumes and save

I think Audio Editor does the same for some reason the Copy / Paste buttons are gone here

Thanks guys, but I don't think this will work. I have one MP3 file with L and R channels that I want to combine and put on both L and R tracks.

Quote Thanks guys, but I don't think this will work. I have one MP3 file with L and R channels that I want to combine and put on both L and R tracks.

Did you even try either approach? Both methods above will combine all the audio contained in each audio clip into a single stereo track.

AVPlayVideo's method is specifically for when each mic has recorded on a single channel and you want to transfer the audio to the other to have balance. My method will work if each mic recorded in mono to both channels as well as when one mic has L only audio and the other mic has only R.

If you need more options, it would help to have sample clips from your two mics to work with. There is a 5MB limit for each attached file here, so please upload to a cloud folder and paste the link here if the clips are larger than that.

Sorry for the confusion. I only have one MP3 file with different sounds on the L&R tracks. I can't copy from one track to the other because it will overwrite what's on the other channel. I guess I could create two files. One with the left track on both tracks and the other with the right track on both tracks and then do what you are suggesting by creating one file from two. Was that the intent?

Quote Sorry for the confusion. I only have one MP3 file with different sounds on the L&R tracks. I can't copy from one track to the other because it will overwrite what's on the other channel. I guess I could create two files. One with the left track on both tracks and the other with the right track on both tracks and then do what you are suggesting by creating one file from two. Was that the intent?

My suggestion, add 2 times the audio in the timeline, one underneath the other.
Open the 1st audio in AudioDirector and copy the channel, L to R.
Open the 2nd audio in AudioDiector and copy the cane R to L
You can now save the 2 audios mixed in Producer.

Quote Sorry for the confusion. I only have one MP3 file with different sounds on the L&R tracks. I can't copy from one track to the other because it will overwrite what's on the other channel. I guess I could create two files. One with the left track on both tracks and the other with the right track on both tracks and then do what you are suggesting by creating one file from two. Was that the intent?

Yes. If you have the content from both mics already contained in a single clip and you want to spread the sound out equally so that both audio channels have the audio from both mics, then make a copy of the orignal clip and duplicate the L on one copy and the R on the other.

AVPlayVideo's approach is exactly what you want!