What does the bolded part has to do with DUP? Its just another way to say multi-periodization. It has nothing to do with doing multiple sports or whatever it seems like you are referring to.
How long did you stick to it?
If you increase volume by added frequency or number of lifts per session, you are no doubt gonna get weaker in the short term. Might take several months until you see gains, but long term it is needed to drive progression.
Sounds like me. I rarely push more than three and a half hours a week these days. No long distance sports to speak of that require more of an investment in time; I warm up, go as heavy as I can for 6-8 reps, a couple of sets of all of 3-4 basic compound bodybuilding exercises. HIIT either on the treadmill or 20 minutes with the jump rope. Done in 50-55 minutes, back to the little kids.
Life, prioritization and other goals aside, you will not get as good progress (if any at all) by doing the same program over and over again once you reach a fairly high level (which you seem to have). You simply cannot add 5 lbs or whatever weight to the bar every time you train and expect that to hold forever. Eventually you have to simply train a lot more to get better.