Could be the difference between either using the built in icons stored internally in Datacad or using External icons when the ini value is set below. If everyone is using external icons, it could also be a difference between the different sizes of the icons, which I see in my Datacad folder but I may have edited mine so I don't know if this is what you would see.
With the dcadwin.ini value set TRUE
Datacad will use the PNG icon files located in the Support Files\Toolbars folder. Locate the the LayerSearch group of icons. Depending on what size icons you use, you locate the icon(s) that seems out of place. Looking at what I have in my folder I see what you are talking about. You might want to create a greyscale version of the Layer_Manager icons to replace the LayerSearchOff icons if that's what you are shooting for. Just keep tack of the file names as you go and you should be all set. For me I am going to create a greyscale version of the LayerSearchOn48.png icon with the magnifying glass to replace the LayerSearchOff48.png because I like to always see the magnifying glass icon for layer search and so I don't confuse it with the regular Layer Manager icon.