Duplicated contacts if stored on the SIM

```
What steps will reproduce the problem?
1. Open Android native contact manager application
2. Create a new contact on the SIM named "Test" having number: +39123456789
3. Create a new contact on the native address book named "Test" having a mobile
number: +39123456789 and an office number: 0123456789
4. Open Imsdroid and look for "Test" contact in the address book list.

What is the expected output? What do you see instead?
Expected output should be to see 2 instances of the contact "Test", one from
the SIM and one from the native AB. There are 3 instances instead, two for the
native AB and one from the SIM.

What version of the product are you using? On what operating system?
Tested on Imsdroid v2.0.520 on Samsung GS2 running Android 4.0.4

Please provide any additional information below.
Removing the contact form the SIM will fix the issue, showing only one instance
of the contact in the AB list.

```

Original issue reported on code.google.com by `android....@gmail.com` on 5 Dec 2012 at 3:52