A B737-700 Captain reported being dispatched with multiple MELs over a four leg assignment. He missed a note on tankering fuel on leg 2 and failed to comply with the MEL.

Narrative

Second leg of four-leg day in same aircraft: Aircraft had three MEL/CDLs; complicating preflight planning. First; lavatories inoperative required managing passengers to not use lavatories onboard; therefore; using restrooms off the aircraft. Second; tankering fuel restrictions with inoperative thrust reverser; OPC adjustments re: same. No problem on the first; third; and fourth flights. I missed the fact the Dispatcher tankered fuel on the second flight. Flight departed with error [untrapped]. It was noticed by the First Officer just after takeoff when the #1 fuel gauge showed an almost instant 1;200 fuel imbalance. He looked at the release to check dispatched planned fuel load; and that is when he noticed the tankered fuel. Captain noted and checked for no tanker fuel on first flight; but missed it during release review during preflight planning and preparation. Flight continued and landed uneventfully as scheduled. Under a multiple MEL/CDL Release; the threat is exponentially increased. Computer guys/IT might explore a 'lockout' feature on some MEL/CDL's. i.e. if thrust reverser inoperative is a factor in preflight planning; tankering fuel option is blanked out.