How do you open CC17 and CC19 at the same time?

[Graphic Squirrel]

Our documents are, for the most part, in CC17.  Now we are moving them all to CC19.  However, during this time-consuming process, I still need to be able to open them in the original version until they all have been moved and proofread.  It involves opening the CC17 version and then comparing it to the CC19 version, meaning I need to be able to open both versions at the same time.

(No matter what Adobe may say, any update can cause movement in our documents, which can cost us thousands if something drops out of a text box, etc.  We've already seen a lot of changes happening when we open CC17 docs in CC19, particularly with leading and shifting of lines and boxes.)

Anyway, years ago when we did the process to move documents from CS6 to the cloud version, we were able to keep both open at the same time so I could move back and forth as needed.  Now when I try to open CC17 when CC19 is open, I get a blue box with a yellow triange and "!" inside.  I have to close CC19 to get CC17 open.  Since I will be constantly moving back and forth for at least 3 months, can anyone give me a clue as to how to keep them both open at the same time?  Changing to PDFs is not an option. I asked the Adobe help team, and they said it was impossible, but another person here is able to do it.  We just can't figure out how it works on his computer and not on mine, when our computers are exactly alike. 

I am using Windows 10, and I did save CC17 when updating to CC19.  I have tried opening CC17 first, then CC19, and vice versa.  I have tried clicking on the file in the windows explorer window as well as using the file, open, etc., method.  All it does is produce that blue warning box and freeze my computer.  Thanks for any help you can give me! 

GS

[Sjaani]

I'm not sure why one person in your office can open both versions while you can't if your systems are exactly the same.

You might need to temporarily install a legacy version of InDesign CC2017.

There is a link to the legacy versions which you can access from your Desktop manager.
If you click the down arrow next to open then choose Manage then Other Versions you'll see a link to Find More Version.

I understand you already have both versions installed, I'm considering the idea that the legacy version will not be directly connected so it may allow the opening of both versions at once.

[Geоrge]

Did you try to use it PC of your co-worker? You can see his screen on your PC by soft as TeamViewer or Radmin. That's more faster than try to check bug that support didn't recognize like a bug.