I found this error scan in a buy & sell site. The upper photo shows the 50 peso bill with smudged ink. The lower banknote scan shows how it should normally look like.
This is the first time I've seen this kind of error. Whoever encounters such must be very lucky considering that banknotes are manually checked for errors before they leave the Bangko Sentral.
The asking price for this item is PhP5000. If you're interested, contact the seller using the link above. The author of this blog is not associated with the seller.