Which Arduino, and sensors (link to datasheet).
Post a diagram, showing how you have connected the sensors.
And if just photo diodes, the value of the pull up or pull down resistor.
What are the average values returned from the analogue readings.
Most Arduinos only have one A/D that is switched between analogue inputs with a multiplexer.
Crosstalk between analogue inputs is common, and worse if input impedance is >10k.
Leo..