Two bluetooth headsets at once?

Hi, I recently got some BT earbuds with an integrated microphone and I wanted to use it for gaming sessions (talk and listen at the same time). I soon discovered that in order to do that, the listening quality must drop dramatically (can't use it both ways unless the heaset has FastStream technology and the PC BT supports it). Anyway, I can either listen OK, or speak without listening, or speak and listen in LQ with the headset profile.

At the same time I bought this to connect my BT headset to my TV:

ELEGIANT Bluetooth 5.0 Transmitter Receiver

Works great BTW. Thing is, in reciever mode (RX), that device uses a built-in mic. I've tried connecting both the headset and the other device under Linux (Ubuntu, my work's PC) and I managed to listen through my earbuds and speak through the device. I should mention here that both devices are always recognized as headsets (both in and out streams), but what I do here is select the earbuds as the audio output and the other as the input. So far so good, apart from some BT interferences. Another thing to mention, if it's worth something, is that I have the earbuds connected to the internal laptop's bluetooth and the other device to an external USB dongle.

Now, I wanted to do the same with Windows, but apparently I can't. As soon as I connect any of them, the other one is automatically disconnected, unabling me to select one as the output and the other as the input. As both devices act as complete headsets (earphones + mic, which they are, actually), I suspect Windows (or whatever BT software) won't allow me to have more than once connected at the same time.

Can I actually do what I'm trying to do, and I what I surprisingly achieved on Linux?

My BT USB dongle (I use the same on both PCs): Csl-Computer Usb Micro Bluetooth-Adapter Class V4.0

Drivers used: CSL-Computer FTP service

Note: I'm not 100% sure that's the dongle I have but it looks the same and mine's brand is definitely CSL.

Note 2: Those drivers seems to have deactivated the whole Win10 Bluetooth management and replaced it with its own.

Now that I think of, would a second dongle only for the mic part work? It should as I understand it, but I don't want to waste money. Let's see if someone can confirm :)

Thanks in advance.

Confirmed, it is a CSR Harmony Bluetooth Stack software limitation. Tried with another dongle, and paired both at once. Thanks anyways hehe.