Fetch all timestamps before converting the set to a list
Fetch all timestamps before converting the set to a list

This is the only way to correctly prevent duplications: for groups, many
layers of the group can have the same timestamps. So we must use a set
until the loop on all layers of the group is done.

ioda-net/geo-infra,ioda-net/geo-infra,ioda-net/geo-infra,ioda-net/geo-infra