If they are both running full time then I agree, and with these two particular applications you are probably correct. Though having one that runs full time and 1 or 2 addition ones that are only run every couple weeks can really help make sure your security has no holes. I know last time I fixed a computer the initial application I used found near 500 Spyware/Adware files, the next one only found around 20, but it was still 20 files that should not have been on there.