I have been having this problem for a very long time, and so far have not found an answer - even going through Chat in Adobe Support. (They didn't seem to know the answer, and when they couldn't provide one, they actually hung up on me.) I hope someone out there has an answer.
When I check my Activated Devices in my Adobe profile online, it shows two, both of which are activated on or around the same day:
<my computer name> on WINDOWS_64
<my computer name> on WINDOWS
It says just above that:
"You can install Adobe applications on more than one computer, activate them (sign in) on two, but use them on only one computer at a time. To activate apps on a third machine, you’ll need to deactivate (sign out) on one of the two current computers first."
So, according to my profile, per Adobe, I should be able to use my Adobe license on two devices at the same time. However, my one computer is acting as though I have signed in twice and therefore using both license simultaneously. If I deactivate one of these, both get deactivated, and if I run Creative Cloud and re-log-in, both devices again show as Activated. If I uninstall and reinstall Creative Cloud and all Adobe apps, the same problem comes up. I even had a computer crash a while back and had to install everything from scratch, and even with that, the same problem came up. No matter what I do, I cannot make my profile see only one computer as Activated - and that is in fact the truth, I am only using Adobe on one computer, not two - and so I have no way to use Adobe on a second computer without Deactiving the only computer I am currently using - which means the idea of running Adobe on two computers is misleading because it simply doesn't work.
How do I get Adobe licensing to see that I actually am running Adobe on only one computer, not two, so that I can, if I desire, install and use my subscription on a second computer without having to deactivate my one computer first? Especially since I should be able to use it on two computers, according to the wording my license page gives me?
I encountered this very same issue. Have you actually tried to activate on a second computer? If not, give it a try and see if you get an error or not. When I was looking into this, I actually had FOUR entries on my list of activated devices - two for each of two computers, one with _64 and one without. I deactivated both entries for one computer, so then I only had two entries, both for the one (new) computer. Then, by chance, I was logged out of CC while looking at these entries online. The list of activated devices refreshed and only showed one entry, the with _64 at the end. When I logged back into CC, the second entry reappeared, the one without _64. Given that I was able to use the apps on both machines when there were 4 entries, and the fact that one of the two seems linked to the machine and one to CC app, I think Adobe does see the two on one system as a single activation. Give it a try!
I have this exact same problem. It's very frustrating. It happens after about a day of the computer being idle. It happens when I open an Acrobat document (or other CC application), and then I receive the message about Adobe DC is having trouble signing you in... so I have to log out of my PC, then log in again and open Acrobat DC again. When I do this, I see the message showing 3 activations: 2 of them correspond to my work PC and home PC, which are valid, but I see my home PC (exact same name) showing as logged in twice (for example, 19 hours ago). After I log out the older home PC login, I can get back into the Acrobat DC (or other) app.
I've connect to the Adobe license portal and ended all of the active sessions, but that doesn't help. I've opened task nanager and killed ALL of the Adobe CC tasks running, then opened CC and attempted to log in again, but then I receive the error that Adobe CC is having trouble logging me in... so I have to go through the logout/login process to get it to work.
This is one reason exactly why Cloud Apps are stupid. I never had issues registering an Adobe premise-based serial number and using it without error until the next major/mintor upgrade. Don't believe ANY software publisher when they say that Cloud apps are for the benefit of pushing updates and providing support to the end user more effectively. Cloud apps are simply the best way that software publishers can guarantee to receive monthly recurring revenue/profit. Cloud apps ensure software publishers never again have to try to convince anyone to purchase upgrades of the software. Either pay, or lose it. Fine, but at least make the product work without forcing the user to close & save every damn thing they're working on to log out/in for it to authenticate properly.