You're not providing a complete
img tag so I might be misreading this, but you can't have multiple
alt attributes like that in the first place.
As for the main question, alt text does get indexed and if you keep repeating things over and over it's not fundamentally different from things like keyword stuffing.
That said, this is not at all what the alt attribute is for.
You should be describing the actual image in there, not cramming a few extra keywords into your document. The alt text is intended to function as a replacement for the image in the case that it doesn't load or the page is visited with software that doesn't or can't display them, like screen readers. In those situations, do you really want your images to be represented by "foobar pics"? This is a direct hindrance to accessiblity–one of the primary purposes of the attribute–that would actually be better served by not having anything in there at all.