If different Master Sources have the same Bibliography field value, that value appears only once in the report's Bibliography page, iirc...
I was wondering if I was remembering this correctly, so I double checked with a little test report. When different Master Sources have the same Bibliography field value, that value actually does appear multiple times in the report's Bibliography page.
It seems to me that this is a bug. But whether it's a bug or whether it's according to design, it would be extremely useful if the behavior could be changed so as not to produce duplicate Bibliography field values.
I was trying to think through whether this problem is a self inflicted wound on my part because of my choice to use extreme source splitting, or whether the problem also exists if you choose to use RM's built-in source templates. The closest thing I could find to addressing the question in any of the Webinars is Webinar #38 Creating a 1940 U.S. Census Citation in RootsMagic from about 39:36 to about 45:20. Bruce explains how to make a copy of one of the built-in source templates and move a couple of fields from the Master Source to the source detail, thereby making sources based on the template be a little bit more lumped. The more fields that are in the Master Source the more split is the source, and the more fields that are in the source details the more lumped is the source.
As Bruce pointed out, if you copy and modify a built-in source template in this manner, you shouldn't have to change any of the sentence templates at all (but I think you might need to change one of the source sentence templates - see below). So I was thinking about the Bibliography sentence template in the Census, U.S. Federal (online images) template that Bruce was using for his example. This sentence template does include jurisdictional information that Bruce moved from the Master Source to the source details in his example. The bibliography sentence doesn't change when you make the source more lumped as Bruce did in his demo. But what happens with the Bibliography list itself with respect to duplicated entries? So I did a more extensive testing, using Bruce's demo as my model for the test.
The answer seems to be that you get one bibliographic entry in the Bibliography for each distinct Master Source that is referenced anywhere in the report. That behavior on RM's part is very simple and easy to understand, and on it's face it doesn't seem to have any problems. However, I see at least two problems with it.
The first problem is that two different Master Sources can produce identical bibliographic entries. I suspect that in what you might call normal use of the built in source templates, this situation would seldom or never occur. You have to create the problem in some sort of pathological manner such as by being an extreme source splitter. In my testing, I made a copy of a Master Source and made a citation for both the original Master Source and for the copy. Both Master Sources obviously had the same Bibliography sentence and the identical sentences both appeared in the Bibliography. So I guess the solution is "don't do that". But a better solution would be if RM based it's construction of the Bibliography based on Bibliography sentences rather than based on Master Sources.
The second problem with RM's behavior in creating the Bibliography is a little more subtle and is exemplified in Bruce's example from the Webinar. After Bruce changes a source template to move a couple of items from the Master Source to the source detail, he doesn't change any of the source sentence templates. Not changing the Footnote sentence template is perfectly fine, and I think also changing the Short Footnote sentence template is perfectly fine. Indeed, being able to move the items from Master Source to the source detail without having to change the source template sentence is the whole point of the exercise.
But I think there is a problem with the Bibliography sentence template in the Webinar. Namely, it contains a data field that is moved from the Master Source to the source detail. It seems to me that nothing from the source detail should be in the Bibliography sentence template. I suppose reasonable people could disagree on this point, but if you want any data from the source detail to appear in your bibliographic entries, you will be sorely disappointed. Once again, that's because the bibliographic entries are constructed on the basis of one per Master Source that is referenced in the report rather than on the basis of one per bibliographic sentence that is referenced in the report. So in the example in the Webinar, after moving jurisdiction to the source details and not changing the bibliographic sentence template, one bibliographic entry will appear for that Master Source containing the jurisdiction for the first reference to the Master Source and the other jurisdictions will not appear in the bibliography. I would contend that either all or none of the jurisdictions should appear as bibliographic entries - user's choice depending on whether or not the jurisdiction is in the Bibliographic sentence template. But that's not the way it works. You only get one of the jurisdictions in the bibliography unless you leave the jurisdiction in the Master Source. And you get one of the jurisdictions in the bibliography instead of none unless you remove jurisdiction from the bibliography sentence.