[Wiki Loves Monuments] multiple refnums on US historic districts disables button

[Peter Ekman]

Many US historic districts have had several expansions, which results
in multiple reference numbers.  In at least two cases, Charleston
Historic District in South Carolina, and one earlier, having multiple
refnums in the table results in the upload button being disabled.  I
removed the extra refnums (leaving the first) in both cases and the
upload button then worked.
Any suggestions for a general fix?

Pete
User:Smallbones