The loop in my R function appears to be running twice - r

Question

I need to add rows to a data frame. I have many files with many rows so I have converted the code to a function. When I go through each element of the code it works fine. When I wrap everything in a function each row from my first loop gets added twice.
My code looks for a string (xx or x). If xx is present is replaces the xx with numbers 00-99 (one row for each number) and 0-9. If x is present it replaces it with number 0-9.
Create DF
a <- c("1.x", "2.xx", "3.1")
b <- c("single", "double", "nothing")
df <- data.frame(a, b, stringsAsFactors = FALSE)
names(df) <- c("code", "desc")
My dataframe
code desc
1 1.x single
2 2.xx double
3 3.1 nothing
My function
newdf <- function(df){
# If I run through my code chunk by chunk it works as I want it.
df$expanded <- 0 # a variable to let me know if the loop was run on the row
emp <- function(){ # This function creates empty vectors for my loop
assign("codes", c(), envir = .GlobalEnv)
assign("desc", c(), envir = .GlobalEnv)
assign("expanded", c(), envir = .GlobalEnv)
}
emp()
# I want to expand xx with numbers 00 - 99 and 0 - 9.
#Note: 2.0 is different than 2.00
# Identifies the rows to be expanded
xd <- grep("xx", df$code)
# I used chr vs. numeric so I wouldn't lose the trailing zero
# Create a vector to loop through
tens <- formatC(c(0:99)); tens <- tens[11:100]
ones <- c("00","01","02","03","04","05","06","07","08","09")
single <- as.character(c(0:9))
exp <- c(single, ones, tens)
# This loop appears to run twice when I run the function: newdf(df)
# Each row is there twice: 2.00, 2.00, 2.01 2.01...
# It runs as I want it to if I just highlight the code.
for (i in xd){
for (n in exp) {
codes <- c(codes, gsub("xx", n, df$code[i])) #expanding the number
desc <- c(desc, df$desc[i]) # repeating the description
expanded <- c(expanded, 1) # assigning 1 to indicated the row has been expanded
}
}
# Binds the df with the new expansion
df <- df[-xd, ]
df <- rbind(as.matrix(df),cbind(codes,desc,expanded))
df <- as.data.frame(df, stringsAsFactors = FALSE)
# Empties the vector to begin another expansion
emp()
xs <- grep("x", df$code) # This is for the single digit expansion
# Expands the single digits. This part of the code works fine inside the function.
for (i in xs){
for (n in 0:9) {
codes <- c(codes, gsub("x", n, df$code[i]))
desc <- c(desc, df$desc[i])
expanded <- c(expanded, 1)
}
}
df <- df[-xs,]
df <- rbind(as.matrix(df), cbind(codes,desc,expanded))
df <- as.data.frame(df, stringsAsFactors = FALSE)
assign("out", df, envir = .GlobalEnv) # This is how I view my dataframe after I run the function.
}
Calling my function
newdf(df)