Two Menu Icons (Hamburger) showing on mobile small screens.

Please see the website http://www.sydneyadventuretours.com . When I load the home page there is a single menu icon and it looks fine but after visiting other pages it loads two menu icons. Once I return to the home page it also shows two menu items and there is a small margin around the whole home page.
The problem is on mobile phones and tablets only. Although the tablets don't seem to have the problem with the margin. It does not occur on desktops if I resize and refresh to a small window. I have fiddled with the customisation, disabling plugins and other tests.