[UX] Append results from other providers even if they are "the same"

[codebude]

Quoted from @DawidGardzinski in the original issue Feedback after 1-2 weeks of using Libris (#78).

Data differs between providers, especially for languages other than the most popular ones, so omitting results when some of the data matches is frustrating when another provider may have better data.

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Author: @DawidGardzinski
Original issue: #78