Duplicate bound attributes should flow through as unbound attributes.

[NTaylorMullen]

If you have a TagHelper with duplicate (same name) attributes only the first attribute gets added to TagHelperContext.AllAttributes. Ex:

<myTagHelper abc="..." ABC="..." />

Today the second one ABC is ignored completely. Instead it should flow through to the output as if it were unbound.

[dougbu]

Same thing happens even when the attribute names have identical case e.g.

 <myTagHelper name="value1" name="value2" />

Only the first name / value pair (containing "value1") will be in AllAttributes.