Adding values to existing tables with RMySQL

I had previously asked a question about Mysql database in using the RODBC library and due to an error in the types, I saw in one of the answers told me about the RMySQL library and I decided to try it.

But I'm not able to add data.frame tables to an existing table.

This is the table I made in mysql:

CREATE TABLE teste ( codigo varchar(5), nome varchar(5) );
+--------+------------+------+-----+---------+-------+
| Field  | Type       | Null | Key | Default | Extra |
+--------+------------+------+-----+---------+-------+
| codigo | varchar(5) | YES  |     | NULL    |       |
| nome   | varchar(5) | YES  |     | NULL    |       |
+--------+------------+------+-----+---------+-------+

And this is the code I'm doing:

library(RMySQL)
#Criando conexão
con = dbConnect(RMySQL::MySQL(),host = "localhost" ,dbname = "Banco",username= "****", password= "****")

#Listando tabelas
dbListTables(con)

#Elementos que serão adicionados
x = list("co1","nome1")
y = list("co2","nome2")

z = rbind(x,y)
colnames(z) = list("codigo","nome")
rownames(z) = NULL

z = data.frame(z)
#==============================

#Escrevendo elementos na tabela
dbWriteTable(con, name="teste", value=z ,overwrite = TRUE,row.names = FALSE)

But when I run the last line (write) my bank creates a new column and all types see 'text':

+-----------+------+------+-----+---------+-------+
| Field     | Type | Null | Key | Default | Extra |
+-----------+------+------+-----+---------+-------+
| row_names | text | YES  |     | NULL    |       |
| codigo    | text | YES  |     | NULL    |       |
| nome      | text | YES  |     | NULL    |       |
+-----------+------+------+-----+---------+-------+

How could I solve this and keep the mysql types?