Make sure you’re running the latest firmware version 1.18. https://wiki.peopoly.net/doku.php?id=moai:firmware
And always format the SD card, then create a folder in the root directory called “gcode”, and then add your gcode files to that folder. And always make sure to power cycle the machine before starting a new print to ensure that memory is cleared.
Never overwrite or delete-then-copy files to the SD card and expect it to work every time. There’s a long-standing bug where the file reader seems to fail to read FAT cluster addresses properly. This can manifest as printing a previously deleted file, or printing a new file that then transitions to printing an older file about half way through, resulting in weird file overlapping artifacts.