multiple exposures on a single plate

[Holomark]

Thanks for all the responses. I think I am starting to understand. Couldn't resist trying so I headed home at lunch and tried. My setup has the reference beam hitting the plate from the side (I still need to work on my setup to get the top reference)
I first shot an image some lego people and parts (2.2 seconds), then turned the plate upside down and shot an image of a skull (also 2.2 seconds). The results are as follows:
The first two pictures show what is seen when illuminating the final hologram from left and right (at approx reference angle)

illuminated from lego side

illuminated from skull side

skull and lego side illum2.jpg (22.83 KiB) Viewed 2220 times

The next three pictures show what is seen when illuminating perpendicular to plate (head on) with three different viewing angles

lego and skull 1

lego and skull 2

lego and skull 3

[Holomark]

The multiple exposure is not as bright/clear as a single image of the skull. Here is a side by side of the skull only (right) and skull with lego (left)
The exposure time for the skull only was 2.3 seconds while both of the exposures with the skull and lego were 2.2 seconds each. The setup was not changed between the skull only and the skull with legos.

The image of the skull and lego may be slightly shifted blue due to the fact that I made the two exposure hologram today at lunch. In my attempt to speed up the process I let the plate dry outside (35 minutes), then painted and let dry in almost direct sunlite. This caused a significant blue shift which subsided somewhat in the 30 minutes between bringing the hologram into the house and the time the pictures were taken. (Both holograms were painted today, but only the dual image plate was also exposed and processed today)

dual image on left - single image on right