The reason some people are getting multiple entries is that they might be signing up to giveaways with a referral link. When someone uses a referral, the original referrer gets a bonus entries.
The URL structure for a Vieworks is :
Referral URL is something like :
*It is not possible for the same user to claim 2 perks.
User referral information can be found in the database download.
For more information on referrals read here