It's not unheard of to have a Fanuc control throw an error in this situation. I have an OMC that throws an error when the tool is already in the spindle. I have an 18MC that ignores it if I'm remembering correctly.
There are many ways to work around this. If not using block delete anywhere in the program, add a block delete ahead of the tool change at the head of the program.
Another way is to start with T1 in the spindle and do not program a tool change at the head of the program.
Finally is to change to a blank tool at the end of the program so T1 is reloaded at the beginning of the program.
The first two of these options leave a small window of potential for accidents if for some strange reason another tool is manually placed in the spindle between one run and the next. Depends on your operational procedures if this potential is worrisome or not.
Not sure if there is a parameter to change this or not. I have a feeling it's a thing chosen by the machine builder. Look in your documentation for an answer to that.