Recommend a app for mac to convert multiple or queued videos at a time

Not free, but I do like iFlicks. If it's a movie or TV show it can even find and embed the metadata for you, very useful for my ripped media collection.

 

Handbrake could be for you: http://handbrake.fr/

It's free, and you can load up as many videos as you want into its queue.

 

After you add a video, click on Add To Queue.

 

Sounds / looks like you added it twice.

 

Did you click start before Add To Queue? A screen recording would be helpful.

 

QuickTime has an integrated screen recorder.

 

What do you see under Show Queue?

 

Why are you converting the last file 3 times? That's why it's returning an error - it's already in your queue with that name.

 

It really should just be:
1) Open file
2) Click start
3) Add second file
4) Click add to queue
5) Repeat 3 & 4

 

In the second image you uploaded there are several copies of some files, therefore the override error message you are getting.

 

Your screenshot clearly shows you are adding the same files multiple times. If you try to add filenames that are exactly the same, of course Handbrake will ask if you want to write over the old files.

 

In the future you might want to open the queue right away so that any duplication that you accidentally start catches your eye. The queue also shows you precisely what will be converted, which title, chapter etc and what the outcome file will be.