It's a well known observation that when someone really smart isn't working in a capacity that utilizes their brain power, they tend to fall into self-damaging patterns. Maura's string of small burglaries and thefts are a perfect example. After graduating from the top of her class in engineering, Maura decided to take a year off to experience life without having the constant threat of deadlines and school in her mind. Five years have passed since then and Maura is still living life as if she's on vacation. She has become a girl who makes last minute plans, steals from small stores and who rarely sleeps in her own bed.
The only thing that didn't change was Maura's ability to duplicate objects. She's able to control which objects she duplicates, where they end up and how many of them there will be. Unfortunately, this little "party trick" does not work on living creatures. Fearing that others will abuse her quirk, she keeps this part of herself well hidden from public knowledge. Maura has only ever told two friends about her ability and thankfully, they have kept her secret and solidified themselves as her best friends.