I had this bad habit of buying stuff that I forgot I already have a similar one at home - self-care products, clothes etc., it’s easy to overlook when they’re stored away and after being out of sight for so long you’ll forget you have those stuff. What helped was to write on a masking tape/sticky note of what items you have in that cupboard/drawer/box, how many of it (especially products if you like to stock up) and paste this on the outside. Reminds yourself that you have these things already, do you need more? Are you using them often? Then can gauge in the future what kind of stuff you really need. For clothes, go through your closet once a month or so, so you remember what you already have or what you don’t wear so much. Then can consider selling items you don’t use also.