Multiple requests for same image with different fragment parts in Firefox (tested in v89.0-64)

<img> element (Vector graphic)

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  #a
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  #b
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  #c
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  #c

<img> element (Raster graphic)

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  #a
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  #b
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  #c
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  #c

background-image (Vector graphic)

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  #a
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  #b
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  #c
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  #c

<image> element (Vector graphic)

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  #a
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  #b
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  #c
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  #c