Multiple product options can not be selected and added to cart

[robotpony]

Example:

https://warpedlino.lemonstand.com/product/sneakers?options[4]=14

• selecting a second option clears the first

Expected:

• both options should be able to have a value
• URL should look like:

https://warpedlino.lemonstand.com/product/sneakers?options[4]=14&options[456]=16

Note that this URL works, but the page can't produce it through setting options.