MT3667 followup MT3811 : unexpected issues not stored

MT3667 followup MT3811 : unexpected issues not stored

As a consequence of previous MT3667 patch, the subscriptionid list was processed.
And unfortunately, since array order is the only relevant information from HTML processing,
it caused subscriptionid to be null for a double edition.
This patch only uses uniq for serials-collection and when passing information to serials-collection page.

Signed-off-by: Colin Campbell <colin.campbell@ptfs-europe.com>