One is for wifi and the other for ethernet. It will switch when it loses one of the connections. My HB2 has separate IPs for each, but only the currently connected one shows on the network. They may be doing some kind of ping check to make sure the other connection is still available. I don’t have a HB3, this is just a guess.
Is the MAC address of the second IP the same as the first? I can’t tell from your example. If the MAC is the same then you probably just dropped the connection during the lease and the adapter got re-assigned another IP. If its different, then perhaps the HB switched from ethernet to wifi during the lease period. The fact that you can ping them both is perplexing. I did a test on my HB2 and only the active adapter responded.
The Wifi and ethernet adapters should have different last 2 or 3 octets but the same first 3 octets.