I'm not affected by this issue but I want to let you know anyway:
This command does not select the last but the previous-last tab.
Is this bug on your list? It still happens in the newest DOpus version.
There have been recent improvements in other areas of Opus where there have long been similar issues that "seem" like timing issues of some kind or another. I think the main area where an improvement was made had to do with running select functions in combination with other functions?
At any rate, hopefully similar improvements can be made in this area - but you can also very easily get around some of them by doing something like:
dopusrt /cmd Go TABDUPLICATE
dopusrt /cmd Go TABSELECT=last
We've have changes planned which will make this a non-issue in the long term, and it doesn't seem worth fixing in the short term (since there are easy workarounds and nobody has said they are affected by it).