SMT CROSSES 1 OF 2 HOLD LINES AND THEN BACKS ACFT TO GET BEHIND IT.

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CLRED TO TAXI TO RWY 10L FOR TKOF. ENRTE TO 10L; THE PARALLEL TAXIWAY CROSSES THE S END OF RWY 18/36. JUST PRIOR TO THIS POINT; IT IS POSSIBLE TO TAKE A R TURN TO RWY 10L FOR INTXN TKOF. WE RECEIVED PERMISSION TO TAXI TO THE 10L INTXN AND HOLD SHORT OF RWY 18. ALTHOUGH RWY 18 ITSELF DOES NOT TRANSECT THIS R-L-R RTE TO THE 10L INTXN; THERE ARE YELLOW HOLD LINES PAINTED ON THE TAXIWAYS. THERE WERE 2 SUCH LINES ON THE W SIDE OF THE 18/36 CTRLINE EXTENSIONS. 1 WAS BRIGHTER THAN THE OTHER; BUT THERE WERE 2. AS WE CROSSED THE FIRST BRIGHTER PAINTED ONE AND STILL SHORT OF THE FADED ONE; GND/TWR ASKED IF WE WERE HOLDING SHORT OF 18. MY FO SAID YES. WE WERE CONCERNED THEN AS TO WHICH HOLD LINE (OF THE 2) WAS VALID; OR WERE BOTH VALID? THERE WAS ANOTHER ACFT OVER 100 FT BEHIND US. SINCE WE WERE APPROX 10 FT PAST THE FIRST BRIGHT HOLD SHORT LINE; I ALLOWED THE ACFT TO DRIFT BACK APPROX 10 FT TO ENSURE COMPLIANCE SINCE TWR INDICATED AN ACFT ON FINAL FOR RWY 36; EVEN THOUGH THE RWY DID NOT EVEN TRANSECT THE CURRENT TAXIWAY WE WERE ON. THERE WAS NO CONFLICT WITH THE ACFT BEHIND BUT THE PRESENCE OF 2 HOLD SHORT LINES IS CONFUSING. IF THE FADED ONE IS NO LONGER VALID; IT SHOULD BE COMPLETELY PAINTED OUT.