IP conflicts between vm's

When 2 vagrants with different ip addresses assigned in their Vagrantfile's, but the same domain configured and up, I see
2 entries for the same domain in hosts /etc/hosts, for instance

10.0.0.38  ldap.example.com  # VAGRANT: 8786....
10.0.0.39  ldap.example.com  # VAGRANT: bb25...

Shouldn't hostsupdater detect this? What should be done?  A warning shown during vagrant up? Just asking.