Welcome to the Q&A Forum

Targeting the same keywords with an additional site could certainly affect impact your existing rankings. You'll essentially be competing against yourself. But it won't make any difference whether the second site is on an addon domain in your primary hosting or on a different host/IP address. Google has so many ways of knowing that two sites are related that goes far beyond what IP they use. There can be instances where a second site for the same topics can be necessary/effective, but you'll want to be really sure that's the best approach as opposed to adjusting your existing site to accommodate whatever it is you're trying to accomplish. You're literally doubling your workload and competing against yourself in the process. What's the purpose of the second site? To go after a completely different market segment? Paul