Read from Device-File gives additional input

Question

I connect a QR-Code-Scanner to my Linux-PC over USB in USB-COM-Mode. When I do so, a file is created: /dev/serial/by-id/usb-Datalogic_ADC__Inc._Handheld_Barcode_Scanner_S_N_E18C59366.-if00

I read from this file like so:

#include <iostream>     
#include <fstream>      
#include <string>
#include <unistd.h>
using namespace std;

int main () {
        while (1) {
                ifstream bufferLink("/dev/serial/by-id/usb-Datalogic_ADC__Inc._Handheld_Barcode_Scanner_S_N_E18C59366.-if00");
                if (bufferLink.is_open()) {
                        string line;
                        while (!bufferLink.eof()) {
                                cout << "Waiting for input: " << endl;
                                getline(bufferLink, line);
                                cout << "+++++++++ Line: " << line << endl;
                        }
                }
        }
        usleep(1000*1000);
        return 0;
}

I then created a QR-Code with the Data: Andre Mantei ist der Beste.

But when I read the QR-Code with my Scanner it gives me a lot of additional output:

Waiting for input: 
+++++++++ Line: Andre Mantei ist der Beste.
Waiting for input: 
+++++++++ Line:  
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: !"#$%&'()*+,-./0123456789:;<=>?@
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: abcdefghijklmnopqrstuvwxyz{|}
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line:  
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: !"#$%&'()*+,-./0123456789:;<=>?@
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`
Waiting for input: 
+++++++++ Line: 
Waiting for input: 
+++++++++ Line: abcdefghijklmnopqrstuvwxyz{|}
Waiting for input: 
+++++++++ Line: 
Waiting for input: 

It happens not always but most of the time. Can anyone explain that behavior ?