Currently working on a large documentary project with a lot of content, I have just switched over to a different computer in the production companies office rather than mine at home. 

in the process of making my selects I bought my sub clips into the timeline and there are many different coloured lines above and below my audio and video clips, but only in some of the timelines. I cant find what they mean in the help center, and they are not organisational colours I have added.

Can someone explain what they mean or do? Its making me a little worried, but at the same time everything seems fine.

Thank you 

Those look like the lines you get when dupe detection is turned on.