Thanks for the detailed report 
At least one problem is copied: CodeChef: Practical coding for everyone = Problem - 29B - Codeforces. Hence all problems have been removed from the Practice section.
ameya13, mayur2305, starkk99, alooooo_lelo, and maoni have been permanently banned from CodeChef. This incident will be conveyed to the relevant college authorities for them to take action as they see fit.
There will also be a ban on any users from that institute conducting contests on our platform for some period of time.