Are you sure you have to release both valves - or do you mean than you opened the centre bleed valve and it didn't free up, and then opened the rearward bleed valve and only then did the pads relax their grip ? If it is the latter, If you had opened the rearward bleed valve first, would that have released the pads without touching the centre valve ? I'm trying to establish which pistons are still applying the pressure after the pedal has been relaxed.
The pedal applies pressure to all 3 pistons when the bike is stationary - the centre one directly, and the outer ones via the SMC. If the SMC is preventing pressure from being released, then the outer pistons will not return. The centre piston however should. If it doesn't, then there is something else going on.
The SMC replacement is a good call and makes sense - especially if Larry has seen the photos. I replaced mine recently when I started to wonder about it, and the bike is only 6 years old - but there will come a time when such spares are no longer available. I thought I'd get one while I could.