What do people think of the fact some projects go KS first (successful) then Indiegogo ?..Hmmmmmmmmmmmmmmmm
If they've had a successful
Kickstarter (and mention it on their IndieGoGo page) then I'd say it differs little from projects setting up a Paypal donation after/during their KS (which several high profile ones have). In such a case, it allows people who missed the KS to join in as well as those who can't/won't deal with Amazon Payments, so could be considered a continuation of an existing campaign.
On the other hand, if a project runs a separate campaign after receiving funding (i.e. there's a definite gap between the old and new campaigns), that looks questionable. It could be done with good intentions ("We've managed to produce a great game but just need a little more to make it aw3s0m3!") but then there's little to distinguish it from those, as Tomimt notes, that can't budget properly.