Hi and welcome. Yorkies are a single coated breed, but, with a mixed breeds, it can be difficult to predict what the 'finished product' will look like. Breeders who breed more than one breed and/or intentionally breed mixes can sometimes, intentional or not, get mixes where they are not quite sure what is in her past...which might result in a double coat...if that
is what you are seeing. I am
not saying this is what happened, just mentioning there 'could' be a possibility she inherited non-Yorkie/non-Maltese DNA as well. She is very cute in your avatar...if you resize the photo, you can upload it. Photoscape is a free download and works great...very easy to re-size photos. I would love to see her in a larger photo!