Hi @sunsilk11
I think, the best way to approach this problem is through combining the results of the clipping together into a single rasters grouped by OBJECTID - use RasterBandCombiner for that. If the clipped rasters have the same extents and spacing, this should work nicely. After that, you will have a single raster with two bands - one band will have DTM heights, and another - DSM. Coerce the raster to points and rename both bands to DSM_Height and DTM_Height, and the output can go directly to geodatabase. FeatureMerger, which is the slowest part of you workspace, is simply excluded.
See the attachment, I added the necessary transformers below your part of the workspace:
dm-1553-processlidar.fmw
If this does not help, do not hesitate to contact me directly at dmitri.bagh@safe.com
Dmitri