www.ultimatehandyman.co.uk

I have a couple of IKEA one sided toilet roll holders to fix
To a hollow wall. My problem is, the two holes on the back plate are very close together so which fixings do I use to get good purchase?

are you talking plasterboard and how close ??

I know the precisely the ones you are talking about (having the day before yesterday fitted three in a commercial kitchen where they were to be used as label roll holders.....) and they are a complete pain in the arris because the screw holes are so closely spaced. Unless you either have a plywood pattress behind the plasterboard, or you can fix something like a 12mm MDF pattress on the face of the wall with something like two more widely-spaced "umbrella" fixings to hold it, these toilet roll holders will tend to rotate or pull off the wall quite quickly (or dig-in to the PB). Tried two umbrellas and two scrunch-up type nylon plugs (e.g. Fischer UX-6) in the past with decidedly mixed results, so these days I glue, pin and screw (with two of the aforementioned "umbrellas") a piece of bevelled MDF onto the wall as a pattress, paint that and fix the toilet roll holder to that wherever possible

BTW by "umbrellas" I mean these:
which are always best set with the purpose-made setting tool if at all possible: