Absurd execution of conditional statements 3 times in Arduino nanov3, how to fix?

Question

Arduino

the first line comes out at startup, the 2nd line when I enter a number, and where do the other 3 come from? according to the logic of the program, in general, only 1 time should enter if because I equalize these 2 variables (xBase and xBase0) and in all cases this happens when I use Serial and Software Serial (via bluetooth) the same thing, and also strictly 3 times (2 extra times)
the code is here

const int baza = 5;
const int col = 6;
const int emi = A5;
int xBaza = 0;
int xCol = 255;
//int xEmi = 0;
int xBaza0 = 0;

void setup() {
  Serial.begin(9600);
  pinMode(baza, OUTPUT); 
  pinMode(col, OUTPUT); 
}

void loop() {
  analogWrite(col, xCol);
  xBaza = Serial.read();
  if(xBaza != xBaza0) {
    xBaza0 = xBaza;
    analogWrite(baza, xBaza);
    writes();
  }
}

void writes(void) {
  Serial.print(analogRead(emi));
  Serial.write("  baza: ");
  Serial.print(xBaza);
  Serial.write("  colector: ");
  Serial.print(xCol);
  Serial.write('\n');
}

Answer 1

void loop() {
  analogWrite(col, xCol);
  xBaza = Serial.read();
  if(xBaza != xBaza0) {
    xBaza0 = xBaza;
    analogWrite(baza, xBaza);
    writes();
  }
}

1. Get into a condition, perform actions. Then you go to the second round. the variable sits, for example, 50, which you assign.
2. Read again, but already reading the port returns you -1, if I'm not mistaken, if not a single character has been read.
Compare: -1 is not equal to 50 and you are in the condition again. The output is performed and the value of -1 is assigned to the variable.
After that, both variables become -1 and you are not in the condition. Because when trying to read the port, the result is -1 and the variable is also -1.
And you are not reading a number, but its ASCII code.
Maybe it will help if(xBaza != xBaza0 && xBaza != -1) {

Answer 2

First of all, you need to make sure that you get what you expect from the port in the sketch. That is, what you "enter" in the port monitor. To do this, comment out your entire if for now, and instead, immediately after the line xBaza = Serial.read(); print the xBaza value to the port monitor. Everything should become clear.

Answer 3

https://www.arduino.cc/en/Serial/Read
Or rather the paragraph
Returns
the first byte of incoming serial data available (or -1 if no data is available) - the int
read() method returns the read data, if any and -1 if there is no data.
Change the code to the following

void loop() {
  analogWrite(col, xCol);
  xBaza = Serial.read();
  if(xBaza >= 0 && xBaza != xBaza0) {
    xBaza0 = xBaza;
    analogWrite(baza, xBaza);
    writes();
  }
}