How to replace all occurrence of a string in file except the first occurrence using Python?

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Python3.6

Here is the content of my file

batch_rollback.txt
------------------------------
pyt_batch_id :- pyt_batch_id

Here multilines of
sql statements
the main pyt_batch_id
task is to
replace pyt_batch_id
from its second
pyt_batch_id occurence
-----------------------------------------

I want to replace all occurrence of pyt_batch_id with any number but not the first occurrence.

I tried the below method and it is working as expected but I don't think this the best approach.

output :-

pyt_batch_id :- 123456

Here multilines of
sql statements
the main 123456
task is to
replace 123456
from its second
123456 occurence


Could anyone please suggest other alternative methods?

What I have tried:

s = open("BATCH_ROLLBACK.txt").read()
s = s.replace('pyt_batch_id', '123456')
f = open("BATCH_ROLLBACK.txt", 'w')
f.write(s)
f.close()

f2 = open('BATCH_ROLLBACK.txt', 'r')
contents = f2.read().replace('123456', 'pyt_batch_id',1)
f2.close()
f2 = open('BATCH_ROLLBACK.txt', 'w')
f2.write(contents)
f2.close()