When systems with high security requirements are used, Roland recommends 2 Independent Double Sheet Detection Systems:
with contacting sensor
with non-contacting sensors
e.g. in Automotive Industry, where very expensive Tools are used.
The reason is:
Each type of detection meets (rarely) situations where Double Sheet cannot be detected, e.g. when two sheets are offset. The second system checks at another position with a different type of sensor and can thus significantly reduce this risk. The majority of Roland customers has confirmed this and is already using two detection systems for one Press Line.
Follow this example!