My mother knew a woman once who kept 52 2lb bags of sugar in her wardrobe. This was not during the war or the period of rationing that followed - I don't believe the oil tanker drivers were even on strike at the time. The woman could not explain her hoarding behaviour, and died some years later with the sugar stash intact. Thinking about it, my partner gets a bit anxious when the household supplies run down to the last four litres of milk or six toilet rolls, and he has yet to see the petrol warning light come on in his car.
Some people may buy extra bottles of the same scent for similar reasons, namely to prevent even the slightest hiatus between their running out of one bottle and being able to get to the shops to buy a replacement. I would say that a hiatus is more problematic in the case of toilet roll and milk, but everyone has different priorities.
Another reason for buying back ups is because a scent has actually been discontinued, where fans of a particular fragrance buy up any remaining stock while it is still in circulation, much like Monsieur Eme in the novel Musc. (See my post of 27th October.) Out of my collection of c50 full bottles, I must own up to one back up bottle of Michel Comte's Shared Water for Women. I found the last case of it in Western Europe at a perfumery shop in Germany - Parfuemerie Nidderau above - and bought one 50ml bottle. I am not sure I would have bothered if Shared Water hadn't been such an unusual scent, inspired by the icy waters and Alpine flora of Switzerland:
The notes are:
Top: Mountain Narcissus, Purple Shiso, Bergamot, Lily of the Valley, Violet
Heart: Freesia, Orchid, Vanilla
Base: Patchouli, Vanille, Vetiver, Moss, Basmati Rice
A third - and perhaps the most common - reason why perfumistas back up their bottles is in anticipation of a reformulation by manufacturers, for example in response to the latest IFRA restrictions, which have in their sights fragrance substances such as oakmoss, birch tar, coumarin and natural jasmine. Lovers of classic fragrances such as chypres are those whose collections are most in jeopardy, and it is they who are investing in single and sometimes double back ups of a beloved fragrance. Now it may be the case that certain perfumes I love are going to be changed beyond recognition, but I tend not to keep up with the latest developments. and as a general rule am more inclined to confront change after the event. If I don't like what has happened, I decide then how to respond rather than aiming off for the eventuality by buying back ups. Just as I turn up to the railway station sometimes to find my train has been cancelled, or my station is closed, and have to figure out a Plan B on the fly.
For the way I see it, if the formulations of all my favourite perfumes remained intact, I would still need many lifetimes to get through all my bottles and decants and samples. So if I went and bought back ups for even 20% of them - hypothetically assuming 20% might be at risk for one reason or another - that's another litre of the stuff that I won't get round to using. Making me not unlike the lady with the bags of sugar...