Time indicator goes faster when playing DVD

[Mr Wolf]

Hi to all!
Sorry if it has already been asked, but I searched and I couldn't find a similar topic.
When I play a DVD, sometimes the time indicator goes faster, i.e. it runs faster than 1 true second.

However, video and audio are not "accelerated", and are played normally.

Is it a bug?

Thanks in advance!

[VLC_help]

Self authored DVD? It is possible that timecodes are wrong, and they could be then displayed like that in VLC.

[Mr Wolf]

Nope, it happens with "normal" DVD I buy.
Btw, I notice it happens in special way when I have another instance of VLC opened. This because I rip dvds in mkv and I compare the mkv to the original DVD, so it happens time indicators are out of sync.