I think your information is out of date here - Medicare doesn't pay multiple surgeries at 25% any more - it would be 50% for the second and any additional procedures.
The MUE is 2, but in my experience, you cannot usually bypass this edit with a modifier any more, so the third procedure will likely deny, but can be appealed successfully with notes. Also, the Medicare carriers where I've worked do not allow multiple units on surgical codes, so this would be billed on 3 separate lines with one unit each. The second and third will need modifiers, which could be XS or 59 or 76, depending on the Medicare carrier's preference.