Lightning, multiple channels to the same node
Not all implementations support multiple channels between two nodes. That is why I would advise against that practice. Also I do not really see an advantage of having two channels. We don't have Atomic multipath routing yet so in general it makes more sense to have larger channels.

Only counter argument I see is that one channel can only have 483 htlcs stimulaniously. So imagine you are an extremely well doing routing node and have a channel to another node of that kind you might want to go beyond 483 htlcs and open up another channel. I would however doubt that this situation will come up in real life as you would probably already have more than 1 lightning node running in such a situation.