The answer is "maybe" depending on several engine parameters. A performance cam can reduce piston pumping pressure at low rpms such that it allows slightly lower octane fuel to work at low rpms. Same for retarded ignition timing. Neither work at very high rpm and the danger is that sheer engine noise will mask detonation noise. Finally, there are several ways to rate gasoline octane. The US and Canada use the 'research' or 'R' method while Europe & the far east use the 'M' or Motor Octane Number method that gives a higher number on the same fuel. Then there's the 'R+M' rating which is an average of the two. Google 'octane ratings'- WIKIpedia has a good description.
Without getting too technical, the simplest way to answer your question is simply to pump a few gallons in and go hammer the engine on a straight road. If a thoroughly warmed up engine rattles on acceleration, return and add more gallons of a higher octane to dilute the first one & raise the anti-knock rating of your combined fuels. If you fill up, you have no room in the tank to do this. Do not waste your time with 'octane boosters'. Some work but most don't and weeding out the useless ones is an expensive task. And if you do find one that seems to help today, there's no guarantee the usually small additive company will make the same product next week.
If you have an expensive modified engine and you get it professionally tuned, they will probably use 102 or even 110 octane racing fuel while tuning, as a safeguard. VPI in the U.S. has about 50 different blends, none of which are cheap or available at any corner gas station. I used to drive another guy's race Pantera with such an engine and the owner ran low one day and added a cheaper 15% blend of gas/alcohol advertised at around 100 octane. We had to bump-start the thing in the gas station- it wouldn't start on the starter. It detonated at idle- you could hear it knocking 20 feet away. He limped it home a few blocks and drained the tank. That fuel had a slightly higher density and his highly tuned Holley couldn't flow enough of it thru the carb jets to work safely. It would have taken a full re-jetting the carb & adjusting the timing on a dyno- again- to allow that 'cheap' fuel to work. Fortunately the adventure did not result in cracking a piston.