Ghost dhcp reservations

[remd]

My setup has 2 lines of 2 CARPed firewalls running opnsense 17.7.6.
Some of my VLAN's show tens of dhcp reservations although I have never made them and the subnet hasnt been used before.
They show up some times on some vlans and then on others seemingly randomly.
The dhcp service is working fine otherwise.

This issue hasn't brought up any serious incident but Ii'd like to understand how this can happen.
Does anyone have an idea ? 

Also for the Opnsense dev's, it would be helpful to be able to select multiple reservations at once, its taking me forever to delete 50-60 reservations at a time..

[remd]

I just realized that the reservations are made again automatically after I delete it, so I cannot remove them.

Is there anything in the opnsense configuration that would auto create dhcp reservations ?

Also when I go to the dhcp, server, interface, there are no reservations for the vlan, they only show under dhcp, leases, "Show all configured leases"

Unless this shows all the dhcp leases that have ever been made (some are however marked as reserved, others as expired), but then again these leases should never have been made as the subnet hasn't been used so far..