It is possible to open >1 connections to the same I2P node
Monero has the same problem that bitcoin once did. You can even connect to yourself multiple times.

Bitcoin issue: https://github.com/bitcoin/bitcoin/issues/21389
comment with proposed fixes: https://github.com/bitcoin/bitcoin/issues/21389#issuecomment-866925116
the merged fix: https://github.com/bitcoin/bitcoin/pull/22112

In monero, `anonymous-inbound` broadcasts the i2p domains to peers. 
`anonymous-inbound` written as `anonymous-inbound=your.b32.i2p:18085,...` will broadcast `your.b32.i2p:18085`. It should only allow `anonymous-inbound=your.b32.i2p:0,...` or perhaps `anonymous-inbound=your.b32.i2p,...`

Im not sure what conditions must be met, but in certain circumstances it will broadcast 18080 as the port. Either way, the fix is to force port i2p peers to only be stored using port 0, and to remove duplicate i2p domains from peerlists.
the merged fix: https://github.com/bitcoin/bitcoin/pull/22112

this is i2p only. Onion works fine and uses ports
