[FFmpeg-user] mix 2 mp4 audio only

[Madovsky]

Hi,

I'm trying to mix 2 streams without to decode reencode
using audio only

ffmpeg -i stream1.mp4 -i stream2.mp4 -vn -map 0:1 -map 1:1 -acodec copy out.mp4

but hear only one audio.

Am I missed something ?

Thanks