`ipfs id` show non-exist addresses

#### Version information:
go-ipfs version: 0.4.18-dev-
Repo version: 7
System version: amd64/darwin
Golang version: go1.11

#### Type:
bug or intended?

#### Description:

Say `192.168.x.x` is my internal IP, `xx.xx.xx.xx` is my public IP, `QmXXXXXX` is my ipfs node ID.

When run `ipfs id`, I observed addresses like
```
"/ip4/xx.xx.xx.xx/tcp/4001/ipfs/QmXXXXXX",
"/ip4/xx.xx.xx.xx/tcp/50119/ipfs/QmXXXXXX",
"/ip4/xx.xx.xx.xx/tcp/10328/ipfs/QmXXXXXX",
"/ip4/xx.xx.xx.xx/tcp/51086/ipfs/QmXXXXXX"
```
Among them, two addresses are generated because of NAT, but the other two, are actually bound to my internal IP, `192.168.x.x:4001` and `192.168.x.x:50119`, not the public IP.

I'd like to know if this is the intended behavior. A short explanation would be welcomed.