What might cause my sample program to forget that already imported datetime?

[Steve]

At the top of my sample program, I have:

import datetime
from datetime import *

But import datetime also has to be entered on line 21 as shown.
The error is printed at the bottom of the code.
Why does the code seem to forget that I have already imported datetime?
=============================================================
import datetime
from datetime import *

d2 =  datetime.now()
d2i = d2.isoformat()

with open("TimeDate.txt", 'r') as infile:
     for BottleInfo in infile: # loop to find each line in the file for that
dose
       BottleInfo = BottleInfo.strip()

       if ((BottleInfo[0:3]== "LBD")):
            BottleData = BottleInfo[0:43].strip()

BottleDataA = BottleData[4:14].strip()
BottleDataB = BottleData[16:30].strip()
BottleDataC = BottleDataA + " " + BottleDataB
print("BottleDataC = <" + BottleDataC + ">")            
print()
d1 = BottleDataC

import datetime  #Why does this have to be here? line 21

dto = datetime.datetime.strptime(d1, '%Y-%m-%d %H:%M:%S.%f')
dti = dto.isoformat()

HoursDiff = int((d2-dto).total_seconds()/3600)
print("HoursDiff = " + str(HoursDiff))
print()

TimeDateInfo=open("TimeDate.txt", "a") 
TimeDateInfo.write("{0:>5} {1:>25} {2:>5}\n".format ("LBD", d2i, HoursDiff))
TimeDateInfo.close()

print("Done")

"""
This is the error I get if I comment out line 21:

Traceback (most recent call last):
  File "F:/Med Insulin codes A/A TEST 10-07-2020/ReadWriteTimeDate POSIX
Samplea.py", line 38, in <module>
    dto = datetime.datetime.strptime(d1, '%Y-%m-%d %H:%M:%S.%f')
AttributeError: type object 'datetime.datetime' has no attribute 'datetime'
"""
This code will be copied into another program as a function and the presence
of import datetime in line 21 causes another error.

==================================================================
Footnote:
The human brain is one of the most complex things known to man.
according to the human brain.