TP-Link UB500 always uses the same MAC address
According to this tweet (https://twitter.com/rioriost/status/1511664649305202690/retweets/with_comments) and one post in Amazon.jp, the TP-Link UB500 adapter uses the same MAC address so you can't install two devices in the same network. I didn't find any source for this in English.
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A tp-link UB500 is a small USB bluetooth device, the kind of thing you would buy to connect a bluetooth mouse or headset to a computer that does not have built-in bluetooth.
This appears to apply to UB400 devices as well.
Here is a tp-link page where they say that it is not possible to use two of the same UB devices in the same place, but a UB400 and a UB500 will work.
https://www.tp-link.com/latam/support/faq/2744/