Select2 Allow re-selection of same value in WordPress

[Michael Mauney]

I want to allow the user to select the same value twice or more times in this form in the order that they choose. Also, how would you assign it to a variable. This is the desire output. Example-1: alpha, alpha, echo
Example-2: charlie, charlie, bravo

Example: 3: xray, foxtrot, whisky,yankee

Example:4: zulu, zulu and etc...                           

I found this example http://stackoverflow.com/questions/36505197/select2-allow-re-selection-of-same-value that does what I need. However I'm unable to get it to work in WordPress. I would like to create a shortcode to use on a registration form.

Thanks

Michael