To be accurate - they should say 'combined experience', but that syntax is so common today that people understand the semantics. Total 'man-yrs' when talking about labor input is a standard construct.
But I'll take Devil's advocate here to in defense of the guy that wrote the story. Two guys each with 25 years is a deeper experience base than one guy with 25 because there isn't going to be 100% overlap in what they were doing. In fact it may amount to more than one guy with 50 in certain ways, so if the idea is to impart how much depth of context the team can bring, I think that syntax is OK. Because there are multiple ways experience can be relevant.
If I have a baseball guy with 50 years he saw Kaline etc in person, but maybe that guy never covered basketball - so two guys with 25 you maybe have 25 yrs of baseball and 25 yrs of basketball. Does that add up to more or less 'sports experience' ? Depends - they each a different value. One 'depth' isn't really better than the other - just different, but it's fair to count both to express the overall experience depth of the group if that's what you want to highlight.