If an in scope question is asked in the worldbuilding community, can the same question be asked in another SE community such as physics if it is also in scope there? If so can these two questions be asked together or should one follow the aother?
Please don't do that
Sometimes questions could theoretically belong to more than one community. Physics.SE and WorldBuilding.SE are good examples, but it's not a good idea to post the same question twice. That means you are not clear on what you are really asking - is it WorldBuilding or Real-Life physics in the example?
Ask the question on the site you think is most applicable. If, like in this case, it does not get any answer, ask a moderator to migrate the question, or alternatively, delete it and re-ask it.
Each site is focused on a specific topic area. If you have a question you feel is too ambiguous, either re-think the question carefully, or do as suggested above.
Many questions people have labeled as being applicable cross-site have been proven to be valid on a single site if written properly and thought through. SE is not a wild west for questions; a question needs to be worked on to be worthy, and if worthy, it will target a specific audience.
Also, if you don't get a response, you can always set a bounty on your question, which will give it much better exposure. This will also mean you have a better chance at getting a good answer.
Looking at the question you're referring to specifically, you're asking the wrong question and not providing enough detail. I have commented on your question and would suggest you update your question with more specific detail — it's not very clear what is going wrong, and without specific information, it is hard to try and answer your question.
The only valid answer I can come up with at this point is that it works perfectly for me based on what you described. The question — as is — is a SF question. However, if you provide specific information, it would be valid on SO since it is referring to the configuration of a development tool.
That depends on why you need to post the "same" question on two sites.
Copy-pasting your question will very likely lead your question to be closed in one of the sites, or both - because it is likely to be unclear or too broad.
I'm lack of example right now, but I think you can ask different questions in different sites about one problem. Technically it's not the same question, obviously.
Just link to the original question in Worldbuilding.SE for background information. Remember to personally edit the question to match with the site's rules.
tl;dr : Don't. If you alter your question to ask about different perspective, then be cautious.