prepared statement with rails and postgresql

gistfile1.txt

connection = ActiveRecord::Base.connection.raw_connection
=> #<PG::Connection:0x00563e2c718098>
[30] pry(main)> connection.prepare('user_id', "select * from users where id = $1")
PG::DuplicatePstatement: ERROR:  prepared statement "user_id" already exists
from (pry):35:in `prepare'
[31] pry(main)> st = connection.exec_prepared('user_id', [786])
=> #<PG::Result:0x00563e26a5bd78 status=PGRES_TUPLES_OK ntuples=1 nfields=29 cmd_tuples=1>
[32] pry(main)> st.each_row do |x|
[32] pry(main)*   p x  
[32] pry(main)* end