No. And NO.
You cannot "double" a PWHT time to "add" enough time to do a weld repair.
1. The COUPON is to verify that the tested welder is doing the specific welding job properly and is using the specified procedure AS WRITTEN and AS TESTED by the original WPS qualification. So, doubling the coupon PWHT doesn't verify anything about whether he can or did weld the coupon properly.
2. If the coupon weld failed, he MUST re-weld a new coupon - you don't get to do a weld repair on a test coupon. The game is not played that way. And, weld coupons are destructively tested (bend test, micrograph of the cut sample, hammer test (if structural plate), etc. If it was an RT test that failed, the coupon still still failed.
Are you sure that your WPS calls for PWHT being required for P1 material only 1 inch thick?