set seed not giving the same results when I sample

[Fredrick orwa]

use data/raw/HARARALLD2024,clear
merge m:1 HoueholdId using Data/raw/Age_s_ALLH1
keep if _merge==1
drop _merge
***keep under 1 years
tab Agegroup,m
keep if Agegroup=="<1 year"
set seed 1
sample 12,count
duplicates report HoueholdId
save data/raw/under1_12missing,replace

Dear all,
Why would set seed produce slightly different results for dataset under1_12missing every time I sample?.I am confused.Kindly assist.
I want to include dataset HARARALLD2024 but it is very big (25000 observations). I don't know whether you will manage to help me without it.
Regards,
Fred

.

[Andrew Musau]

It is the m:1 merge that results in different sort orders, not the sample command. Ensure that a consistent sort order is maintained after the merge.

[Fredrick orwa]

Thanks Andrew.It was surely a merge issue.So I sorted my data after merge and got the same results