CPR Y CLB THROUGH OCCUPIED ALT HAD LTSS FROM CPR X. SYS ERROR.

Narrative

HOUSTON CTR HAD RECEIVED FLT PLANS FROM MONTEREY CTR ON 2 JETS DEPARTING THE MONTEREY ARPT AND CLBING OVER LAREDO VORTAC AND TO CONTINUE ON THE SAME RTES UNTIL THE SAN ANTONIO VORTAC AT WHICH TIME THE RTES WOULD DIVERGE. I (THE RADAR CTLR) OBSERVED BOTH ACFT ON MY SCOPE WHILE THEY WERE STILL WELL (50 OR 60 MI) INSIDE MONTEREYS AIRSPACE. I IMMEDIATELY OBSERVED THAT THE BACK ACFT HAD ABOUT AN 80 KT OVERTAKE ON THE FRONT ACFT; AND THE BACK ACFT WAS LOWER BUT CLBING AT A GREATER RATE THEN THE FRONT ACFT. I ATTEMPTED TO CALL MONTEREY CTR TO MAKE SURE THEY WERE AWARE OF THE SITUATION AND TO OFFER AN OFF COURSE VECTOR TO THE ACFT IN BACK. MONTEREY CTR WOULD NOT ANSWER MY CALL. A MIN OR 2 LATER I TRIED TO CALL AGAIN AND STILL GOT NO ANSWER. I TRIED A THIRD TIME AND STILL GOT NO ANSWER. THE ACFT WERE ABOUT TO ENTER MY (USA) AIRSPACE AND WERE LESS THAN 10 MI APART AND LESS THAN 2000 FT VERTICALLY AND THE REAR ACFT STILL HAD AN 80 KT OVERTAKE. I HAD MY ASSISTANT CTLR CALL MTY AND HE FINALLY GOT HOLD OF THE MTY CTLR. I TOLD MY ASSISTANT TO HAVE MTY ASSIGN THE REAR ACFT FL290 AND A HDG OF 030 DEG. MTY ACKNOWLEDGED. WE THEN OBSERVED THE ACFT ENTER USA AIRSPACE AND THE REAR ACFT FLEW THROUGH FL290 UP TO ABOUT FL304 BEFORE HE STARTED BACK DOWN TO FL290 AND THEN SLOWLY BEGAN A R TURN. SEPARATION WAS LOST BTWN THE 2 ACFT AT OR ABOUT THE COMMON HOUSTON CTR/MONTEREY CTR BOUNDARY. MONTEREY CTR DID NOT PROVIDE POSITIVE (OR ANY OTHER) SEPARATION; NOR DID THEY PROVIDE A TIMELY HDOF ON EITHER ACFT; NOR DID THEY PROVIDE TIMELY COM CHANGE. THE ACFT IN FRONT WAS AN CPR X LTT FILED FOR FL370 AND THE REAR ACFT WAS A CPR Y; MDT; FOR FL410.