If two users edit values in the same Tenant’s common variable set the last save overwrites the previous one. As per this.
I know we can pickup the “lost” changes in the audit log but its not ideal, is this likely to change in some way? be it warnings as happens with project variables or anything else? And if yes, is there any timescale (months, years)? If nothings immanent we’ll probably need to look to move variable set values into source control.
I can’t currently provide an accurate estimate as to which version this will end up in, but if you follow the GitHub issue the milestone will be updated with the release version once it is added.