won't work if multiple same flags are given

[tunnckoCore]

for example

var expand = require('expand-args')
console.log(expand(['--set=a:b,c:d', '--set=c:d']))

throws error on line 146 - i fixed the line, throws from 173 - fixed, throws from expand-object.

I'm think snapdragon can come here too :)

[jonschlinkert]

yeah I was thinking that too :)