Must not happen with properly functioning SPI interface, and proper programming. While values being read may be different, e.g. first time 0xc5, second time 0x130, the MSB must never be larger than buffer size (in you case of 2K is 0x08). If you get > 0x08, then there’s some problem with SPI interface or issue in logic accessing chip through SPI (e.g. MSB/LSB swap).
Edit: another source of intermittent issue - broken workflow by using concurrency - with interrupts of threads.