As Patrick H says - check to ensure there is no charge remaining in the barrel.
It looks to have been painted, so removing the paint may well show up some more marks, particularly underneath the barrels and on the outside of the locks (there should be another, smaller perron there)
It also looks as though it will dismantle without tools. Half cock the two actions. The metal slide on the forestock will slide out sideways one way or another and then carefully lift up the barrels keeping hold of the butt - a hook on the breech will be there to secure the barrels in the standing breech so it may need to be lifted some way.
So why painted (badly)? Either someone did not know what to do with it and/or it was in a real mess - probably after de-rusting. It will need a ramrod - almost certainly of wood with brass caps on each end (fairly standard on these Belgian guns). Here is a more expensive one:
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