Attached please find my OSPF diagram.
R3 in area13 has two link connected area0 via separate ABR(R1 & R2), the backup tunnel has been set a higher interface cost to insure it will not be choosed if the SDH is UP.
Actually i found the route 10.13.0.0/16 in R1 was correctly choosed SDH as next-hope, but R2 choosed the backup tunnel directly even if the route metric is higher. In my idea, the R2 should choose R1 as next-hope and via SDH to reach 10.13.0.0/16.
If i shutdown the backup tunnel manually, R2 will choose R1 as next-hope for the route 10.13.0.0/16.
I must got some misunderstand in the OSPF area design, anyone help to clarify will be much appreciated.