DFPlayer Mini. file name vs file index

i have copied 5 mp3 files in sd card and it have names 001.mp3 to 005.mp3. and played it in the order 1-5.

0x7e, 0xff, 0x06, 0x03, 0x00, 0x00, 0x01, 0xfe, 0xf7, 0xef

i used the above command to play first file, but instead it played 5th file.

0x7e, 0xff, 0x06, 0x03, 0x00, 0x00, 0x02, 0xfe, 0xf6, 0xef

similarly instead of 002.mp3 it played 004.mp3. 

Then i reversed the playing order, that is 5→1. but when i used the following command, that is for playing 005.mp3, it played 001.mp3. 

during copying if i copied in the descending order that is 5→1, the first file positioned will be 005.mp3. and when passing command for playing 001.mp3, it might treated the 1 as file index instead of file name. Is this true?. file index is valid and file name is irrelevant?.