Balancing between multiple IPs on a single WAN

I recently added some address space to a single WAN connection and assigned two IPs in a NAT configuration with a server. I assumed that all outbound traffic would be using the one IP that was set as the outbound in the NAT configuraton, and that the additional IPs would only be used for inbound traffic. However I have seen some evidence that both IPs are being used for outbound from that server. Can anyone confirm that this is way that it actually works with two IPs in NAT on a single WAN?

If you tie a specific IP address from the WAN connection in an outbound mapping, it should be using that IP. You can open a support ticket via our website for further investigation: