so true, driverchris - but not always from the till-jockey.
Slightly off-topic; A tale from the other side of the counter:

Serving. Customer makes small purchase with £20 - no big deal. Same customer makes second small purchase with second £20 - I'm wary, but they both appear as valid as scottish currency ever does; and we all sometimes forget things, or need a bit of change. Same customer tries to make third small purchase with £20. Mental "piss-take" alarms sound. Third note has same serial as one of the first two, and while I'm discretely checking this he asks me to change a small bunch of others, most of which I can see have the same numbers.

I stall the customer, whilst I call over the (co-incidentally, older) duty manager (who earned at least twice as much as me) and discretely explain situation. Explain situation again, emphasisisng the bit about matching numbers. Patiently explain situation as simply as possible, that serial numbers should *never* match; while watching her furrow her brow in a vain attempt to understand the situation. Customer then runs away, but not before she's handed him back some of his dodgy notes. I die a little more inside.
(The Incredible Sulk Finally remembered his password on, Thu 30 Apr 2009, 18:16, Reply)