Is this still heterochromia?

my uncles dog has each eye 2 colors. on BOTH eyes, the tops are green, then speckle down to blue. remember, it's not green one eye, and blue the other. no. both eyes are both green AND blue. he doesn't seem to have vision problems, as he can play fetch perfectly fine (indeed, he'll play fetch for hours, stopping only to drink water). i was wondering, is this an extreme case of Heterochromia, or is it something different?