Are these single band or 3 band imagery? What is the pixel type and bit depths of the input rasters and the output raster? Are you comparing the range or the individual pixels? How far off are the values?
Hi Alisa,
Do the rasters all have the same underlying grid? In other words, do the rasters that are going into the mosaic, all have perfect cell alignment? If they don't you should expect the value to change somewhat because they will be resampled. What resampling do you have set in your environments? Also, is there any overlap between the inputs? What options were set in the Mosaic Operator parameter?
If you have support, you should open an incident so an analyst can have a look.
Best,
Eric