These are really strange results, possibly to the point where lab error could be suspected. First, was this mass spectrometry-based testosterone testing? It's been reported that the standard test is reactive to nandrolone. But that would push results in the opposite direction. HCG would, if anything, also tend to push the results in the opposite direction, with the later measurement higher. But the dose is small. Was SHBG measured? If SHBG dropped significantly then it's anticipated that total testosterone, but not free testosterone, would drop some with the same dose of testosterone. However, the effect should not be this large. Did you test free testosterone by any method? In the absence of large changes in SHBG these readings should roughly track total testosterone, thus confirming or disputing the results.
Finally, was your cypionate/propionate blend 80%/20%? Propionate is going to make measurements inherently less stable and more sensitive to timing and absorption conditions.