This may be intuitively correct, but to my mind it is architecturally wrong. A good language should not tolerate ambiguity and offer to guess which behavior is correct.
As far as language specs go, Go's is really quite concise and I strongly encourage everyone I onboard to spend an afternoon reading it end to end at some point in their first couple weeks.
If there were no duplicate URL field, say they were called FooURL and BarcoURL, you could access them as `opts.FooURL` and `opts.BarcoURL`. They are both fields of `opts`, via embedding. It's just that FooURL is embedded directly, while BarcoURL is coming from two levels of embedding.
