Additional variants (after the first) aren't correctly sent to form

When I add additional variants (2, 3, etc.) to a new experiment, I get this error when trying to create it:

"The variant must have a name and a non-zero assignment_weight."

They do have both, but what appears to be the problem is that the input fields for variant 2, 3, etc. don't have the right name -- or any name at all. The screenshots show what I mean.

Using Chrome, OS 10.7, Shrimptest 1.0b3, and WordPress 3.2.1.