How to find out, why two libraries aren't working along?

Hey guys,
I want to use the Conceptinetics.h and the LiquidCrystal_I2C.h, but when I am including both of them, I get an error message.

HardwareSerial0.cpp.o (symbol from plugin): In function `Serial':

(.text+0x0): multiple definition of `__vector_25'

/tmp/359861568/build/libraries/Conceptinetics/Conceptinetics.cpp.o (symbol from plugin):(.text+0x0): first defined here

/home/ubuntu/opt/tools/avr-gcc/4.9.2-atmel3.5.4-arduino2/bin/../lib/gcc/avr/4.9.2/../../../../avr/bin/ld: Disabling relaxation: it will not work with multiple definitions

collect2: error: ld returned 1 exit status

exit status 1

I would like to delete the part of the library that isn’t working along, so how do I find out which part is the problem? :confused:

For completition, my code:

#include <Conceptinetics.h> // DMX-Module
#include <Wire.h>               // Communication via SDA/SCL
#include <LiquidCrystal_I2C.h>  // Communication for Display

String version = "Ver. 0.3 alpha";
const int LCD_Adress = 0x27;         //display adress (0x27)
const int LCD_Characters = 16;
const int Maxlines = 2;              // Size display: 2 rows with 16 characters
LiquidCrystal_I2C lcd(LCD_Adress,LCD_Characters,Maxlines);

int CursorLine = 0; // first character
int DisplayFirstLine = 0; // first row
char* MenuLine[] = {"1. Set DMX","2. Set Time","3. Set Mode","4. About"};
int MenuItems;
int menu=0;

const int Button1 = 3; // Back-Button (red)
const int Button2 = 5; // Go-Button (white)
const int Button3 = 6; // Enter-Button (green)
unsigned long lastDebounceTime1 = 0;  // the last time the output pin was toggled
unsigned long debounceDelay1 = 50;    // the debounce time; increase if the output flickers
int buttonState1=HIGH;             // the current reading from the input pin
int lastButtonState1 = LOW;   // the previous reading from the input pin
byte button1 = 0;  // becomes 1 if pressed
unsigned long lastDebounceTime2 = 0;  
unsigned long debounceDelay2 = 50;
unsigned long buttonCounter2 = 1000;
int buttonState2=HIGH;
int lastButtonState2 = LOW;
byte button2 = 0;
unsigned long lastDebounceTime3 = 0;
unsigned long debounceDelay3 = 50;
int buttonState3=HIGH;
int lastButtonState3 = LOW;
byte button3 = 0;

//int dmx=EEPROM.readInt(0);

void setup ()

  MenuItems = sizeof(MenuLine)/sizeof(MenuLine[0]); //Menu

  lcd.clear(); // Change to menu
  lcd.blink(); // Position of cursor will blink

// Serial.begin(9600);

// end of setup

void loop (){
  buttoncheck(); //main menu
  if (menu==0 && button2==1){
  if (menu==0 && button3==1){

Thank you guys in advance!

That dmx library tries to define UART TX and RX interrupts, but those are already defined in the builtin hardware serial library.... I don't see how that library ever worked; I would suggest contacting the creator of the library and asking under what conditions it will work...