This is a dual USB ports device which based on WCH CH32V208. And both of these 2 USB ports are acted as USB CDC. In this way,
you can transfer data by USB COM between 2 PCs.
For more information, you can find it in:
https://mc.dfrobot.com.cn/forum.php?mod=viewthread&tid=315504#pid537648
And here is the video