adjust regex in duplicate check

[ProxiBlue]

The regex used to find duplicate url_keys are giving false positives if the given url_key ends in -[number]

for example:

19th-century-filipino-basket-with-lid-acc-7311-5219 would result in 19th-century-filipino-basket-with-lid-acc-7311-5219-1.html as the request url.

[infabo]

LGTM. +1