Colombia - Serial numbers on the reverse - on purpose or by mistake?

Except for a 20 cents note issued by Banco Nacional (de la República de Colombia) in 1900, which has the serial letter on the obverse and the serial number on the reverse, all Numista entries for Colombia have the serial letters and numbers printed on the obverse.

Can it be confirmed that the Colombia 2000 Pesos series of banknotes bearing the large Santander's image  

N#205278

N#224036

N#237758

are the only banknotes issued by  Banco de la Republica (Colombia's Central Bank) that have the serial number printed on the reverse?

Does anyone know if this was by mistake or done on purpose?

Hello 🤖

Without pictures, it will be very difficult for anyone to help you. Could you please post clear pictures of each side of your item?

Please note that this is an automatic message. Feel free to ignore if it is not relevant.

It seems like on this specific denomination they chose to put the serial number on the reverse.