I have a customer that wanted to put TeamViewer on 2 of his systems and once the TV is installed, both systems have the same ID.
Windows 10 LTSB
Thank you for your message.
Your customer probably cloned the image of his device.
I think that the following article would be interesting for him: How do I use TeamViewer on cloned systems?
I hope this could help. If not, do not hesitate to ask your questions here.