Am I hearing things?

Elizabeth  one other thing you might look for the two breakers that share the common neutral need to be ganged. 2  20amp breakers with a common neutral will trip like any other 20amp breaker they won't draw anywhere close to 40amps. The load wouldn't be balanced on the neutral which is what would trip the breaker actually breakers they are suppose to be ganged with the hot on seperate phases. 

I don't get the 25amp breaker on a simple branch to a single 20amp receptacle. Those are not common breakers and are mostly used for AC units and water heaters. You said they did some work on your AC are you sure you're not looking at the AC breaker? If not it should be switched to a 20amp breaker. 

The two breakers are NOT ganged, And I know about the fail on 40 amps. The two sides are ON OPPOSITE PHASE (which I mentioned) so it would be impossible to have 40 amps on the neutral.. What would happen if both legs had 20 amps is: the power would be flowing from line A HOT through the neutral only to where it joins line B neutral, and the power from line B (opposite phase) HOT only to where it joins line A neutral. The Two HOTS are basically together at 240 volts when the lines are using equal power. They 'power' is still only 20 amps, but at 240V? Only when one line is using more power does the neutral to the breaker box come into play.
 As far as the power cares..At least this is my minimal understanding of it as a blind fool can know, basically.
And generally the power in wall was done at least back in 1960 ish. When the building was built. I bet today the code would not allow it. Back then??

No its the sound room labeled. I have 2 dedicated lines with 2 outlets 3 inches apart. I hooked up the Bryston to the new line with the 10 ga wire and my power plant to the other one. sonically everything is great now but I will change it out to a 20 amp breaker. Thanks for everyones input. Memebers here look out for each other. 

In the 60's they did the common neutral to save copper, some houses back then were wired with aluminum. Code now is the breakers have to be ganged on common neutrals  hot needs to be on seperate phases. the reasoning is both of those breakers need to be tripped before you work on either line.