Manila Conference Of 1954 Surchage

I can't find any information regarding this stamp:

I see the number 5 is over the original stamp #10, so that makes it a surcharge right?

Maybe that isn't right. I mean..... why would there be a lesser value on the stamp? (5 overprint on the #10).

I can't find any information what the Manial Conference of 1954 has to do with the surcharge?

Thank you all!
I have a LOT more Overprint stamps in questions, lolol.....
SueStamps

Suestamps, interesting observation ...it looks like 5 cents was the first class fee at the time...looks like they took a 10 cent stamp and made it a 5 and announced the 1954 conference while they were at it...lets see if others agree or disagree !

Sue, that is a Scott's #613 issued in 1954.
The catalogue says, "Manila Conference 1954. The surcharge is arranged to obliterate the original denomination."
No other explanation why.
I don't think surcharges alway increase the price of a stamp. I've seen lots the do the opposite, like here.
There is also a 18c on 20c issue as well (SC#614)

Surch.: abbreviation for surcharge, overprint.
Surcharge: 1: an overprint which changes the denomination of a stamp either up or
down. 2: Universal Postal Union language is additional fee. 3: used on Britain and
British Colonies issues may mean postage due. 4: can change a regular definitive
stamp into a semi-postal stamp, or regular issue to an air mail issue. 5: zuschlag
(Ger.).
Surcharge Postage: Grenada, Trinidad and Tobago, postage dues.

9900 posts vs. 6600...i will always be in your shadow !!

In fact, surcharges more often than not reduce the value of the stamp, rather than increase it. The reason's obvious when you think about it. It would have been quite expensive to forge that original 10 Centavo Philippines stamp if you were going to use it to defraud the post office. It would be much cheaper to set up a bit of type and overprint/surcharge a higher value onto the basic stamps. If you could buy the underlying stamp for 10 centavos at any post office, return to your print shop and, for the cost of a fraction of a centavo, turn it into a 15 or 20 or whatever centavo stamp ... attractive business!

I mentioned on another tread that a surcharge can be more or less then the orignial stated value.
But the main reason for a surcharge is usually the lack of stamps in the needed value stated so an overprinted surcharge is required.

I believe in this case there was no need for the surcharge except for the fact the rate was reduced for more stamps of that value could be bought, sold & used from this convention!