Hi, Ali,
In order to protect IP, we do not suggest customer reads application code or data of LPC1765 and writes to flash of another LPC1765.
But I suppose that the FlashMagic has the function to read flash in ISP mode.
Pls download FlashMagic tools from the link and have a try:
https://www.flashmagictool.com/download.html&d=flashmagic
Hope it can help you
BR
XiangJun Rong