Well that's a curious problem, and I don't know why that's happening.
I can put GOOGLE and EBAY on two separate URL containers in a dashboard. I can put GOOGLE and GOOGLE MAPS together. EBAY and GOOGLE MAPS work.
But toss mapquest into the mix, and you get the behavior you're seeing.
This doesn't answer your question, but it might help you drill down more into what's happening.
Can you attached a packaged workbook example so we can help you better. Both should show but there may be a filter somewhere thats showing either or as appose to both
Right. The two URLs you have right now are working, but if you change one to mapquest it doesn't show. Change it to just about anything else and both work again. (I tried ebay. CNN. MSN. Scottrade.)
I also tried mapquest witgh a specific address in the URL, just in case mapquest was hokey like that. Didn't matter.
For the record, the http://tndtableau.cloudapp.net/gmaps/gstreetview.html?lat=<Locn Phy Latd Txt>&lon=<Locn Phy Lngt Txt> URL you have in the packaged workbook doesn't show anything meaningful, but it still goes to the web page and shows something, as opposed to mapquest, which just gives a blank white screen in that container.
Perhaps you need to open a support ticket for this. To me, the expected behavior should be that Tableau will show in the container whatever IE or Firefox shows for any URL.
FYI--I talked with a Tableau helpdesk person re dual URL actions (one URL using mapquest), the reply I recieved is as follows:
It is possible, but when this has been done in the past it was necessary to have one action point to a container on the dashboard and the other open up a web browser.
I still to try this with my work, but just wanted to share the information. Angie