I am not sure what you are trying to say here. The blood on the faucet has only Amanda's DNA. One can find a photo of Amanda's pillow which also has a small stain, consistent with a bleeding ear. BTW, one has to look at the photo of the faucet carefully to distinguish what is actually blood from the reflection of the brown ceiling. This biological matter may be unrelated to any other in the bathroom.
The mixed DNA from the shared bathroom comes from the bidet, among other places. Even Colonel Garofano was unimpressed with the sampling technique used (they sampled all the way down to the drain plug--for Pete's sake). If you introduce blood onto biological matter that is deposited into sinks, bidets, or bathtubs, you will produce mixed DNA. If Guede had cleaned up in Laura and Filomena's bathroom, it is very likely that one would observed mixed samples from Meredith and one or both of them (of course the police would have to take their reference profiles first).
That's a good one! I've read a lot of interesting interpretations of the evidence, but I've never before read that the blood on the faucet is not actually blood, but is instead the reflection of the ceiling.