"La Maison de la Monnaie Belge" has nothing to do with the official belgian mint.
https://www.lamonnaiebelge.be/
It is just a company that sell coins. Almost all what they sell are replica's/copies/restrike copies.
They say they are Original coins, or coins struck with the Original dies. That is not correct.
They sold me a belgian coin, also with certificates and all it need to make it look genuine:

I should be cautious with these coins....
The 'coins' that they sell are not a good investment. If yours are really gold, you will get the value of the gold.
Please use Google Translate:
All these sites have 1 conclusion: the coins are fake and the company is 1 big fraude.
https://www.test-aankoop.be/klagen/publieke-klachten/publieke-klacht?referenceid=CPTBE00072717-64
https://juridischforum.be/viewtopic.php?t=60517
https://www.tijd.be/netto/beleggen/Let-op-voor-munten-waarvan-u-niet-rijk-wordt/9327739
https://onlinebroker-reviews.com/opletten-met-het-belgische-munthuis.php
https://www.hln.be/regio/deurne/inspectie-onderzoekt-actie-munthuis~a71c93cc
https://radar.avrotros.nl/forum/viewtopic.php?f=27&t=56599&start=20
http://www.zilverenlach.nl/NederlandseMuntenhuis_Beoordeling.htm
I hope you did not pay to much....
PS : there has never been struck a gold 20fr of Leopold I in 1914 (at least I can not find it in the Morin catalog)
I suppose you mean Albert I ?
http://users.skynet.be/peterdegroote/BelgFrank/Serie/Alb1-NED.html