diff --git a/src/genpinmap/genpinmap_arduino.py b/src/genpinmap/genpinmap_arduino.py
index 0c6489bc..4d1e9555 100644
--- a/src/genpinmap/genpinmap_arduino.py
+++ b/src/genpinmap/genpinmap_arduino.py
@@ -156,19 +156,31 @@ def get_gpio_af_numF1(pintofind, iptofind):
     return mygpioaf
 
 
+# Return 0 if pin/signal not already in the list
+def isPinAndSignalInList(pin, signal, lst):
+    return len([item for item in lst if item[0] == pin and item[2] == signal])
+
+
 def store_pin(pin, name):
+    if pin in [p[0] for p in io_list]:
+        return
     # store pin I/O
     p = [pin, name]
-    io_list.append(p)
+    if p not in io_list:
+        io_list.append(p)
 
 
 # function to store ADC list
 def store_adc(pin, name, signal):
+    if isPinAndSignalInList(pin, signal, adclist):
+        return
     adclist.append([pin, name, signal])
 
 
 # function to store DAC list
 def store_dac(pin, name, signal):
+    if isPinAndSignalInList(pin, signal, daclist):
+        return
     daclist.append([pin, name, signal])
 
 
@@ -176,72 +188,110 @@ def store_dac(pin, name, signal):
 def store_i2c(pin, name, signal):
     # is it SDA or SCL ?
     if "_SCL" in signal:
+        if isPinAndSignalInList(pin, signal, i2cscl_list):
+            return
         i2cscl_list.append([pin, name, signal])
     if "_SDA" in signal:
+        if isPinAndSignalInList(pin, signal, i2csda_list):
+            return
         i2csda_list.append([pin, name, signal])
 
 
 # function to store timers
 def store_pwm(pin, name, signal):
     if "_CH" in signal:
+        if isPinAndSignalInList(pin, signal, pwm_list):
+            return
         pwm_list.append([pin, name, signal])
 
 
 # function to store Uart pins
 def store_uart(pin, name, signal):
     if "_TX" in signal:
+        if isPinAndSignalInList(pin, signal, uarttx_list):
+            return
         uarttx_list.append([pin, name, signal])
     if "_RX" in signal:
+        if isPinAndSignalInList(pin, signal, uartrx_list):
+            return
         uartrx_list.append([pin, name, signal])
     if "_CTS" in signal:
+        if isPinAndSignalInList(pin, signal, uartcts_list):
+            return
         uartcts_list.append([pin, name, signal])
     if "_RTS" in signal:
+        if isPinAndSignalInList(pin, signal, uartrts_list):
+            return
         uartrts_list.append([pin, name, signal])
 
 
 # function to store SPI pins
 def store_spi(pin, name, signal):
     if "_MISO" in signal:
+        if isPinAndSignalInList(pin, signal, spimiso_list):
+            return
         spimiso_list.append([pin, name, signal])
     if "_MOSI" in signal:
+        if isPinAndSignalInList(pin, signal, spimosi_list):
+            return
         spimosi_list.append([pin, name, signal])
     if "_SCK" in signal:
+        if isPinAndSignalInList(pin, signal, spisclk_list):
+            return
         spisclk_list.append([pin, name, signal])
     if "_NSS" in signal:
+        if isPinAndSignalInList(pin, signal, spissel_list):
+            return
         spissel_list.append([pin, name, signal])
 
 
 # function to store CAN pins
 def store_can(pin, name, signal):
     if "_RX" in signal:
+        if isPinAndSignalInList(pin, signal, canrd_list):
+            return
         canrd_list.append([pin, name, signal])
     if "_TX" in signal:
+        if isPinAndSignalInList(pin, signal, cantd_list):
+            return
         cantd_list.append([pin, name, signal])
 
 
 # function to store ETH list
 def store_eth(pin, name, signal):
+    if isPinAndSignalInList(pin, signal, eth_list):
+        return
     eth_list.append([pin, name, signal])
 
 
 # function to store QSPI pins
 def store_qspi(pin, name, signal):
+    if isPinAndSignalInList(pin, signal, qspi_list):
+        return
     qspi_list.append([pin, name, signal])
 
 
 # function to store SYS pins
 def store_sys(pin, name, signal):
     if "_WKUP" in signal:
+        if isPinAndSignalInList(pin, signal, syswkup_list):
+            return
         syswkup_list.append([pin, name, signal])
 
 
 # function to store USB pins
 def store_usb(pin, name, signal):
     if "OTG" not in signal:
+        if isPinAndSignalInList(pin, signal, usb_list):
+            return
         usb_list.append([pin, name, signal])
     if signal.startswith("USB_OTG_FS"):
+        if isPinAndSignalInList(pin, signal, usb_otgfs_list):
+            return
         usb_otgfs_list.append([pin, name, signal])
     if signal.startswith("USB_OTG_HS"):
+        if isPinAndSignalInList(pin, signal, usb_otghs_list):
+            return
         usb_otghs_list.append([pin, name, signal])
 
 
@@ -944,7 +994,7 @@ for mcu_file in mcu_list:
     print(" * I/O pins found: %i" % nb_pin)
     # io_list.sort(key=natural_sortkey)
     # for io in io_list:
-    #     print(io[1])
+    #     print(io[0] + ", " + io[1])
     print("done\n")
     clean_all_lists()