She doesn't fit the bill for a double dapple that might have issues. She looks like a dapple with patch work. Double dappled doxies with genetic issues have large areas of white. I'm talking more then a patch. They tend to take up the majority of the dog. A dapple can have dapple in their eyes with no problem. Here is a link to see what I mean between the difference. Coat Patterns
From my understanding a litter of double dapples can vary with solids who have no problems to those with excessive white that have issues. She's a gorgeous pup! I would say at first guest she is a chocolate with patchwork and a white patch on her chest. Beautiful baby.
Doubles can have only a little white on them, however that's not common. She has perfectly normal eyes though, so no worries there. Single dapples regularly have blue or parti coloured eyes, so that's not a sign of a double.
I've seen doubles with very little white have hearing and/or vision problems. The amount of white doesn't always mean whether or not the dog'll have vision or hearing problems, it just depends on where the double dilution gene hits, sometimes it may only be in an eye or an ear.
The merle defects only affect doubles, never singles as they need both dilution genes (one from each parent) to cause the issues, a dapple to dapple breeding will have roughly 1/4 solid pups, 1/2 single dapple, and 1/4 double dapple. A solid to dapple breeding will have 1/2 solid and 1/2 single dapple, and a double dapple to solid breeding will have an entire litter of single dapples.
If Mouse (who is deaf and vision impaired) were to be bred to a solid, we would have all dapple puppies with no defects... However, if those pups were bred to a dapple, than there is a great risk of those double pups being deaf and/or sight impaired.