Arduino and 2 Adafruit Fingerprint modules working together I want to do a project with fingerprint access control. But my client wants one on both sides of the door (inside and outside). Now I am using this product Adafruit Fingerprint module but I don't want to enroll each person on each fingerprint module. I want to look at enrolling each employee on 1 of these modules and then via arduino "SYNC" the fingerprint models between each other. Is this possible? Can someone maybe point me in the right direction or am I just insane HAHAHA. Look I can do the route of programming/enrolling each person on each module. But we life in a real world and at some point the fingerprint model/id's are not going to match up. And then there is going to come a problem with my online software. As well sorry for my bad lanuage  :)
Yes, you can easily do that. This finger Print sensor works over Serial communication. 

You can have multiple Serial devices connected to your Arduino UNO using SoftwareSerial library.

All you have to do is to create multiple instances of Adafruit_Fingerprint initialized with different SoftwareSerial objects. i.e.

// pin #2 is IN from sensor1 (GREEN wire)
// pin #3 is OUT from arduino to sensor1  (WHITE wire)
// pin #8 is IN from sensor2 (GREEN wire)
// pin #9 is OUT from arduino to sensor2  (WHITE wire)
SoftwareSerial mySerial1(2, 3);
Adafruit_Fingerprint finger1 = Adafruit_Fingerprint(&amp;mySerial1);
SoftwareSerial mySerial2(8, 9);
Adafruit_Fingerprint finger2 = Adafruit_Fingerprint(&amp;mySerial2);


Now, you can use finger1 and finger2 for your finger print operations. (previously referenced as only finger)

In order to understand Serial Communication with multiple serial devices, have a look at this Arduino.cc Offical tutorial.

Hope it helps.