Combine same referece and keep different page numbers

I have two citations that point to the same reference (but different page numbers). I ended up combining these two citations.

(EPA 1999, 10) (EPA 1999, 55)

EN automatically deleted the second instance (because it’s a duplicate) but the problem is that the two citations were different page numbers.

Looks like this: -(EPA 1999, 10)

When I look at Edit and Manage Citations, both citations are there, but you only see one in the output.

Is there a way for EndNote to combine the page numbers, so it looks like (EPA 1999, 10, 15)?

Maybe a setting I’ve missed to turn off?

What output style are you using?  Can you attach it here for testing? 

So I tested it with an APA6th style, and you are correct.  The easiest workaround though, is to insert the citation once and then put in both page numbers as you want them to appear.  I put in 10, 55 and got the correct output (Endnote X8/Word 2016 on a PC).