r - Get rid of anomaly appearing in the colour legend (ggplot2) -

i have following plot:

you can notice in colour scale, first item (lte only: red-dashed line), there anomaly in dashed line. somehow line gets thinner before actual whitespace.

this anomaly disappears when don't plot data of blue color:

note dashed line looks ok now.

i use following code plot data:

ggplot() +    stat_summary( data = cellblocksutilizationul_lteonly, aes(x=roundedrealnumvehicles/2, y=(value), colour=as.factor(1),  lty=as.factor(1) ) , fun.y=mean, geom="line", size=1 ) +   stat_summary( data = cellblocksutilizationul_clust, aes(x=roundedrealnumvehicles/2, y=(value), colour=as.factor(2), size=as.factor(clusteringdistance), lty=as.factor(2) ) , fun.y=mean, geom="line", alpha=0.80 ) +   scale_linetype_manual(values = c(2,1) , name  ="protocol\ntype" , labels=c("lte only", "lte4v2x")) +   scale_color_manual(values = mycolors , name  ="protocol\ntype" , labels=c("lte only", "lte4v2x")) +   scale_size_manual(values = c(0.4, 0.7, 1.2, 2, 3, 4, 5) , name = "clustering\ndistance (m)" , labels=c("100", "200", "300", "400", "500", "550", "600"), guide = guide_legend(override.aes = list(colour = mycolors[2])) ) 

i can't explain cause of problem (it seems in legend 2 types of sizes plotted) can remove effect override.aes= , setting size= inside color scale.

+ scale_color_manual(values = c("red","blue") ,            name  ="protocol\ntype" , labels=c("lte only", "lte4v2x"),           guide = guide_legend(override.aes = list(size = 1))) +