beetles mixed in with new crickets

[modest chameleon]

Hello,
I recently purchased 1,000 crickets online and when they arrived they had around 50 small black flying beetles crawling around and some larva as well. When I opened the box the beetles started flying out so I rushed them out of the garage. I read recently where someone was infested with carpet beetles from their crickets they bought online so I'm a bit worried.
However, I also read that some people leave the beetles and larva in their tubs as a cleaning crew. I'm confused as to whether these are beneficial or an infesting pest.

I've been scanning through the forums as I'm sure this has been addressed but cannot find a definitive answer.
Thanks in advance.

 

[RobSquared]

Yes those guys help out ALOT with cleaning your cricket enclosure. I used to clean them out all the time but when I started leaving them in there the smell went down and overall cleanliness was better. However, if the flyers try and get out I swat them because I do not want them flying around the house

 

[junglefries]

I always have the little cleaner worm like slug things in my cricket boxes of a 1,000. Never seen them turn into the beetle, but have seen very tiny beetles in the boxes, also. They eat the dead. It's the hitchiking spiders I have a problem with.