# using Merge 
lists <- list(eset,eset3)
eset_both <- inSilicoMerging::merge(lists, method='NONE')
 
# using combine 
eset_both2 <- combine(eset, eset3)
 
# Manually
neweset<-ExpressionSet(assayData=cbind(exprs(eset),exprs(eset3)[featureNames(eset),]))
phenoData(neweset)<-new("AnnotatedDataFrame",rbind(pData(eset),pData(eset3))[sampleNames(neweset),])
 
# Compare results 
sum(exprs(eset_both)[featureNames(neweset),sampleNames(neweset)]!=exprs(neweset))/length(featureNames(neweset))
sum(exprs(eset_both2)[featureNames(neweset),sampleNames(neweset)]!=exprs(neweset))/length(featureNames(neweset))