How can I overlap geojson collection with an other one with leaflet?

I create this with leaflet with 2 geojson collection.

My issue is I want blue to be above orange. And is it possible to don't see the orange when blue is above ? and how to do it ?

This is my code (I have the same code for both geojson)

var fc2 = {
    "type": "FeatureCollection",
    "features": [unionA2]
}

L.geoJson(fc2, { // initialize layer with data
    style: function (feature) {
        return {
            color: "#ea6621"
        };
    }
}).addTo(map);