Hello! my friends & author
Now a days so many people are copying your themeforest item and selling on other marketplace, so in feature become this type problem don’t contact to Envato team (Because Now a days Envato team receiving so many complaints Unfortunately, sometimes this can be a lengthy process as Envato team have many reports to follow up on and a lot of sites either take a long time to respond to theme, or don’t respond at all.You might find that it’s much quicker and effective when you take action yourself. ), simple contact to that marketplace where you find your duplicate item, Or
We have created some resources that can help you with the steps you can take.
Please find these via the following links:Sending a DMCA takedown notice
How to use the Whois Lookup Tool
https://help.market.envato.com/hc/en-us/articles/202501564
Tools you can use to report illegal links of copyrighted work
Additionally, we recommend that you read the following post which contains helpful details to protect your copyright.
If anything else please share here
We hope its help to all Envato community member 
Regards,
ilmosys team