Question about mobile phones and user agents

Are there unique user agents for mobiles like there is with pcs or do all models of iphone for isntance look the same to a site like instagram?

Need to know if I can skip the step of having to make a unique phone for each account and just clear cookies on the same phone for footprint purposes.

Asking a bit some ppl have said emei numbers.

So I guess me real question is how do you do the equivalent of randomizing user agent like you do on pcs but for phone emulation? -i read there is something for bluestacks but I'm using android-sdk.