Question

Is it a bad ideea to have 2 keys for identifying a valid information ?

Company information table serves the car wash table and also the car service table

Let’s say We have a table that has the categories

=== Category Table ===

id
category_name
active
position
path

Then i have the table that serves the two different tables.

==== Company Information ====

id
parent_id
category_id
company_name
company_adress
bank_name

The two tables that are from different categories

==== Car wash table ===

id ( this will be the parent id in company information )
category_id
...other_fields

=== Car service table ===

id ( this will be the parent id in company information )
category_id
...other_fields

Answer 1

There is nothing fundamentally wrong with having the same same key in one table referenced by multiple foreign keys in other tables. It is quite normal.