Sequence value sets backwards

We have noticed a unique problem. We have set sequence objects on two tables. We have a 3 node cluster of Cheetah with one primary (prim) and 2 seconday servers (sds1 and sds2). Our primary database (prim) crashed. So sds1 became the primary server. Now when we tried processing a file in this setup, the sequence number was found have been reset to an earlier value. This caused duplicate sequence in the tables mentioned above. In one of the tables the field had a unique index and hence was returning errors. However in the other since it was not unique, it allowed the duplicate sequence to be recorded. This has caused problems in the application. I request the Informix GURUs to help me resolve this issue.