VM backup policy run 5 times at night without schedule it

Hello we are running Netbackup 7.6.0.2 on window server 2008 SP1 R2.

We have a policy from type VMware, that run full backup to an auto select vm clients 1 day at the weekend every month.

All the backups were good and in time untill we upgrade our evironment from 7.5.0.6 to 7.6.0.2.

As a result of this, the next weekend after the upgrade every vm client backuped 5 times, backup after backup in spite of the fact that this weekend it sould not be backuped.

Please help me why it happened, and how I can prevent it in the future.

Thank you,

Sisso