I think KubotaTech is correct about the filters. My M 9000 takes 2 identical filters and I think in this case the only difference between it and your is HP.
I don't know on the color off your particular filters you just installed but I found this out by accident. My local dealer sells JD and Kubota tractors. JD is their primary even though 50hp and under Kubota out sells JD 3 to 1 and 50hp and above it's 2 to 1 according to their salesman. The Kubota filters they sell are always white. I never thought anything about it and just assumed that the blue looking filters only came from the factory on new tractors. After several trips to the parts counter (for PM supplies) and seeing the parts guy hand JD parts out like free candy and then telling me that what I needed had been back ordered or they just sold the last on a few minutes ago I got fed up and went looking for a new dealer.
I found a little hole in the wall dealer about 30 miles from me and stopped in one day. All the guys here talked to me like I was their best friend and we had known each other all our lives. Pleased with my treatment I asked for a engine oil filter for my L 3000. The parts man stood up (never even touched a parts book) and walked back to a shelf, picked up a filter and handed it to me. I opened the box and the filter was blue just like the one that came on my tractor when it was new. After seeing that I told him what I had been getting and asked what the difference was.
The white filters are
made in Mexico
for Kubota and the Blue filters are
made in Japan
by Kubota. After I got home I compaired the blue one to a white one. Right out of the box the white filter had some kind of white looking powder on the rubber seal that I had been told by my local dealer was from the manufacturing process but the blue one didn't have this. The blue filter felt like it weighed twice as much as the white one did so that told me that either it had more filter media in it or the case was made better. In either case it should be a better filter in my opinion.
After asking more questions at the new dealer I found out that they were the first dealership that carried Kubota tractors in the US. They said that they would never carry the filters from Mexico bacause they weren't up to there standards. The owner told me that he only wanted the best for his customers and that getting the original Kubota parts was part of his job. I found out another service that he offers that no other dealer has ever offered me before is that they will order the parts/filters that I need and have them shipped from Kubota right to my door at no cost to me. I have done this several times since then. Call them up and tell them what I need and in a couple of days it shows up and a few days after that I get a bill from the dealer for the parts. I dont know if this is something that this one dealer does or if all of them can do this and just don't tell you but it may be worth checking into.