17.thor.ragnarok.2017.720p.bluray.dual.audio.-h... Online

So the to add = the specific audio language names after "Dual.Audio".

Based on the naming pattern, the missing from that filename is likely the audio/subtitle language tags after "Dual.Audio". 17.Thor.Ragnarok.2017.720p.BluRay.Dual.Audio.-H...

17.Thor.Ragnarok.2017.720p.BluRay.Dual.Audio.-H... So the to add = the specific audio

Here's the breakdown: