When modeling a system in double pass in sequential ZEMAX, certain solves are required to mimic the same physical lens in the second pass.  Furthermore, for tolerancing, the coordinate breaks describing the tilts and decenters must be setup by hand, and the TE** operands can no longer be used.  To ensure that any tilt performed in the first pass is picked up by the second pass of the beam, user defined operands (TUDX, TUDY, TUTX, TUTY, TUTZ) must be used to replaced the built in element tilt/decenter tolerance operands.

Both before and after tolerancing such systems, it is important to verify that your ZEMAX model is representing reality.  After all, you don't want the second pass decenter or tilt differently from that of the first pass, or your tolerance results won't be an accurate representation of the perturbation!

REFERENCES

ZEMAX Optical Design Program User's Guide, ZEMAX Development Corporation