Understanding the IR Emitter / Detector I pulled off of an inkjet printer
I believe your part is a dual channel IR position sensor. I can't find your exact part, but I did find a datasheet for something very similar although this has 8 pins, this is the OPB822:



However, yours only has 6 pins. I guess that as you suggest, two pins are the infrared LED, so I think that the two detectors share the same LED.

The other four pins are the opto couplers, and you can identify them using an multimeter that can measure the voltage drop of a diode. Try touching two of the probes to two of the pins while switching the transmitter LED on and off, if the reading changes with the LED, then you've found two of the pins you need.

The dual sensors can then be used to sense which direction its travelling along the strip, and how far.