Q:

Conflicting layer styles for geojson in Leaflet map

Assigning a style to a geojson layer but it is visualising with the aforementioned style as well as the default blue style assigned to geojsons. Can't work out what is causing 

<!DOCTYPE html>
<html>  
<head>
<title>Global Terrorism Attacks </title>
<meta charset="utf-8" />
<script src="http://code.jquery.com/jquery-2.1.0.min.js"></script>
<link rel="stylesheet" type="text/css" href="css/own_style.css">
<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet/v0.7.7/leaflet.css" />
<script src="http://cdn.leafletjs.com/leaflet/v0.7.7/leaflet.js"></script>
<script type="text/javascript" src="geojsonLayer.js"> </script>
</head>
<body>
<div id ="container">
    <div id="header">
    <br><b>Global Terrorism Attacks</b><br><br>
    </div>
</div>
<div id="map">
<script>
    var map = L.map('map').setView([41,-1],2);
    var CartoDB_All = L.tileLayer('http://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png', {
        attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a> &copy; <a href="http://cartodb.com/attributions">CartoDB</a>',
        subdomains: 'abcd',
        maxZoom: 19
    });
    CartoDB_All.addTo(map); 

    var layerOrder=new Array();
    function popupcall (feature, layer) {
        layer.bindPopup("<h1 class='header'></h1>" + feature.properties.admin);

    };

    function doStylegtd(feature) {
    if (feature.properties.armassault >= 0.0 &&
            feature.properties.armassault <= 500.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#2b83ba',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    if (feature.properties.armassault >= 500.0 &&
            feature.properties.armassault <= 1000.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#80bfab',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    if (feature.properties.armassault >= 1000.0 &&
            feature.properties.armassault <= 1500.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#c7e8ad',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    if (feature.properties.armassault >= 1500.0 &&
            feature.properties.armassault <= 2000.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#ffffbf',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    if (feature.properties.armassault >= 2000.0 &&
            feature.properties.armassault <= 2500.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#fdc980',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    if (feature.properties.armassault >= 2500.0 &&
            feature.properties.armassault <= 3000.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#f07c4a',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    if (feature.properties.armassault >= 3000.0 &&
            feature.properties.armassault <= 3017.0) {

        return {
            color: '#000000',
            weight: '1.04',
            dashArray: '',
            fillColor: '#d7191c',
            opacity: '0.6',
            fillOpacity: '0.6',
        }
    }
    }
    L.geoJson(geojsonLayer, {
        style: doStylegtd
        }).addTo(map);
    L.geoJson(geojsonLayer,{
        onEachFeature: popupcall
    }).addTo(map);  

    //jamie.setStyle(function(feature) { return secondStyle; });
    //L.Util.setOptions(jamie,{style:secondStyle})
</script>
</div>

A:

You are adding the same geojson layer to the map twice:
L.geoJson(geojsonLayer, {
    style: doStylegtd
    }).addTo(map);
L.geoJson(geojsonLayer,{
    onEachFeature: popupcall
}).addTo(map);  

The second one of these is giving you the default blue outlines. 
Try: 
L.geoJson(geojsonLayer, {
    style: doStylegtd,
    onEachFeature: popupcall
}).addTo(map);

