Can't run sketchup on two machines

I’ve recently updated my computers to version 2020 but now find that I can’t use sketchup on my desktop and my laptop (obviously not at the same time). Prior to converting to 2020 I was able to use sketchup on both machines but now I get message saying that “This device is not authorized. Please sign in to continue.”
The only thing I have found that works is to deauthorize all machines, then sign in on the machine I intend to use, which is cumbersome to say the least. I must be missing something so if one of you could give me some advice it would be greatly appreciated.
I have MacPro desktop and a MacBook Pro laptop, both running macOS Catalina 10.15.6

Maybe you where signed in in Version 2019, as well. Somehow, this counts as an activation. You may be signed in on two devices ‘of the same kind’ (eg. 2 computers - 2 tablet/phone - 2 Viewers)
So you have discovered the ‘Deauthorize Devices’? That’s good.
If other’s are looking for this, here’s a link:

What Mike says it probably what was happening. The deauthorize all devices should have removed the 2019 sign in as well, and so as long as you’re signing in with two 2020 computers, the old 2019 sign ins shouldn’t be haunting you.