well, without the dwg that you copy & pasted this legend in which has the problem, having the legend dwg won't help.
But may I ask why are you copy & pasting when you should be xreferencing which have multiple advantages:
1. any changes in original legend dwg, all other dwgs with this referenced in would automatically update
2. if you already have a block name in the current dwg like "Lighting fixture" that looks graphically different than what's in the legend dwg and you copy & pasted the legend into it, the "Lighting fixture" will now look different.
3. if you already have a Text Style "ARCH_48" in the current dwg and you copy & pasted this legend into it, the Text Style will change and look like your current dwg.
4. if you already have a Layer called "Elec" with a different Color like 3 in the current dwg and you copy & pasted this legend into it, the Elec Layer Color will change to 3.