I'd say it's too front-loaded. A 2-level dip gets you mirror image
1+Wis times per day, which will be a lot
for any decent Wis-based character, and the ability to provide everyone else with a free Vexing Flanker feat. The mirror images are also significantly better than real mirror images even before you start boosting them with additional class features, what with being unable to distinguish them with hearing, and with being able to perform different actions from you entirely... this seems to be what you're going for, but it's too much, too early.
After reading the first paragraph, I expected this to be something like the Swiftblade, except with mirror image
and monk abilities instead of haste
. I think that would be a good direction to go. Take a look at the class
if you haven't already, and consider revising this class to look more like that one. Stretch it out into 10ish levels, spread the abilities out so it's not so front-loaded anymore (really, the main reason not to dip this is the garbage Skill Focus requirement, and there are ways to get that essentially free), and either mix it with some spellcasting, give it more unique abilities, or let it progress more of what a monk gets normally (this last option probably isn't a good one, monk is a scattered mess that doesn't work well with itself).
It's kind of an interesting idea, though... sort of like a summoner's instant army, except yours is totally fake.