Incident management increase 10 ids a incident

Hi Experts,

I have configured the incident management in SolMan 7.1 SP12.

I tested to create incidents then the incident IDs increase 10 number a incident like the following.

I think the incident number increases 1 number a incident.

For example, 9000000002 should be taken instead of 9000000011.

I cannot understand why this is occurred.

Could you please let me know why this is occurred and how to resolve this?

Regards,

Takashi