In case if we convert a clean db (just created and filled by config data) to DM mode and start to use it then server generates IDs like 100000000000001 in tables events, alerts and may be other.
Note first part "1000" which should be "1001" for NodeID=1 according to specification https://www.zabbix.com/documentation/2.2/manual/appendix/faq
Of course it's not critical, but it can mislead in case of troubleshooting and investigation some mysterious problems.
I'm not sure what we have to do with this.
Maybe we could document it somehow on the doc page.