That is a very project managery view of things. And in a simple system you might be right. In a complex system multiple different things can cause same looking problems.
Let's say you are not working on a "number box" (whatever that is) but a drone airplane. Your costumer reports that the drone become unresponsive and crashed.
You investigate and find that there is a buffer overflow which sometimes gets triggered in the navigation system which trashed the memory and lead to the loss of the drone. You develop a patch, and additional testing etc etc and you deploy the fix.
A year later a drone crashes again. You do the investigation and this time you find in the engine control there is an edge case which causes it to shut down the engine under rare circumstances.
Was the first fix not a fix? If I correctly interpret you it wasn't because the "drone becoming unresponsive and crashing" problem still persist. Obviously that is not a useful way to look at the work if you actually have to develop the fixes.
Obviously there was two different problems, and they both need fixing separately (often by different teams). Just because you are not aware of the second bug when you deploy the first fix doesn't make the first fix not a fix.
Of course you might say in this hypothetical the "problem was not the same" but you only know that after you have investigated. If there are no reasons to suspect the second bug, and during the testing of the first fix things appear to be working you have no way of knowing that.
Let's say you are not working on a "number box" (whatever that is) but a drone airplane. Your costumer reports that the drone become unresponsive and crashed.
You investigate and find that there is a buffer overflow which sometimes gets triggered in the navigation system which trashed the memory and lead to the loss of the drone. You develop a patch, and additional testing etc etc and you deploy the fix.
A year later a drone crashes again. You do the investigation and this time you find in the engine control there is an edge case which causes it to shut down the engine under rare circumstances.
Was the first fix not a fix? If I correctly interpret you it wasn't because the "drone becoming unresponsive and crashing" problem still persist. Obviously that is not a useful way to look at the work if you actually have to develop the fixes.
Obviously there was two different problems, and they both need fixing separately (often by different teams). Just because you are not aware of the second bug when you deploy the first fix doesn't make the first fix not a fix.
Of course you might say in this hypothetical the "problem was not the same" but you only know that after you have investigated. If there are no reasons to suspect the second bug, and during the testing of the first fix things appear to be working you have no way of knowing that.