Avoid duplicate in registration with multiple Idp
45134
How to use OAuth only for login, not create account unless the user wants one
89483
Multiple passports and the 90 / 180 rule
61642
Prevent multiple instances of a given app in .NET?
123625
Prevent Multiple Form Submissions (Server side)
71644
How can I remove existing duplicate accounts and records at once?
9064
Is it a good practice to show a sign-up or registration form as seperate parts rather than in one go?
95434
Is it easy to enter the UK multiple times on the same Business Visitor Visa?
15016
Can I have multiple valid ESTAs in different passports?
96195
Can we have multiple  in same ?
35506
remove duplicate from list and create non-duplicate id set
112077
How to check if a value already exists to avoid duplicates?
101594
Can I rely on reading SQL Server Identity values in order?
51360
jQuery clone duplicate IDs
138642
Should the "closed as duplicate" message be altered?
6664
ActionBarSherlock + Google Maps API v2 Duplicate Id
28090
duplicated id with fragment
115061
Multiple instances of same device on I2C bus