- if ($t+86400-$lastid > $pc9x_past_age) {
- dbg("PCPROT: dup id on $t <= lastid $lastid, ignored") if isdbg('chanerr');
- return;
+ # note that this is where we determine whether this pc9x has come in yesterday
+ # but is still greater (modulo 86400) than the lastid or is simply an old
+ # duplicate sentence. To determine this we need to do some module 86400
+ # arithmetic. High numbers mean that this is an old duplicate sentence,
+ # low numbers that it is a new sentence.
+ #
+ # Typically you will see yesterday being taken on $t = 84, $lastid = 86235
+ # and old dupes with $t = 234, $lastid = 256 (which give answers 249 and
+ # 86378 respectively in the calculation below).
+ #
+ if (($t-$lastid)%86400 > $pc9x_past_age) {
+ dbg("PCPROT: dup id on $t <= lastid $lastid, ignored") if isdbg('chanerr') || isdbg('pc92dedupe');
+ return undef;