Are you using their online batch geocoder? Or their desktop application? I've never used their desktop application, so I can't speak to the validity of it. However, when I needed 300 some addresses geocoded, their online batch coder was perfect. Here's the link for the batch geocoder: Free online database geocoding services from Texas A&M Geoservices
If you have ArcGIS for Home edition (and the credits) you can also use the Esri geocoding engine.
Otherwise, if you're really strapped for credits and aren't comfortable uploading to TAMU, QGIS (Welcome to the QGIS project! ) is a free GIS platform which can support a Python plug-in that will geocode for you through the internet (installation instructions for plugin: MMQGIS ). This solution isn't as accurate as Esri's offered geocoding, but if you're just making a map for fun, practicing, et cetera, it will make shapfiles for you that can be imported into Esri's available layers. I used this when I was experimenting with GIS and learning how shapefiles worked.
File > Add Data > X,Y Data... inside Arcmap and choose excel sheet with the X,Y add them to the option fields and choose the coordinate system they were collected in typically the geographic WGS84 or NAD83.