If you want to check if the same cells express 2 different genes you can plot one gene on the x-axis and the other gene on the y-axis using the plot() function.
From this code just update the gene names (here “Kdm5d” & “Uty”) to your 2 genes of interest!
gene_A <- which(rowData(sce)[,2] %in% "Kdm5d")
gene_B <- which(rowData(sce)[,2] %in% "Uty")
plot(logcounts(sce)[gene_A,], logcounts(sce)[gene_B,], xlab="Kdm5d", ylab="Uty")
The genes along the x-axis only express the gene_A, genes along the y-axis only express gene_B, and genes along the diagonal express both genes.