Avoiding overriding variables when importing a subscript using dot notation - powershell

Question

When I write complex PowerShell scripts, I use to split the scripts into separate files:
main.ps1 to contains the logic
imports\xxxx.ps1, imports\yyyy.ps1, ... to provides custom functions
The main.ps1 file imports in the current scope the functions using the dot command after having computed the path relative to the current directory. Ex:
$CurrentDirectory = Split-Path -Parent $MyInvocation.MyCommand.Definition
. "$CurrentDirectory\Imports\Maths.ps1"
Process-Multiply -x 10 -y 10 # assuming there's a function in the maths.ps1
This is working as long as I don't overwrite the variables within the imported scripts. For example, if my subscripts again declare a $CurrentDirectory variable, it actually overwrite the variable from the main script. I guess it's because of the dot notation (in opposition to the & notation).
Is there a way to avoid this ? Is it possible to have "local" variable for a script ?
Here's a full reproductible sample:
File main.ps1 :
$CurrentDirectory = Split-Path -Parent $MyInvocation.MyCommand.Definition
Write-Host "`$CurrentDirectory from main.ps1 : $CurrentDirectory"
. "$CurrentDirectory\Imports\Maths.ps1"
Write-Host "`$CurrentDirectory from main.ps1 : $CurrentDirectory"
Process-Multiply -x 10 -y 10
File Imports\Maths.ps1 :
$CurrentDirectory = Split-Path -Parent $MyInvocation.MyCommand.Definition
function Process-Multiply{
param(
[Parameter(Mandatory=$true)][int]$x,
[Parameter(Mandatory=$true)][int]$y
)
$x * $y
}
When running the main.ps1 script, the output is :
$CurrentDirectory from main.ps1 : C:\temp\xx
$CurrentDirectory from main.ps1 : C:\temp\xx\Imports
100
As you can see, the $CurrentDirectory variable is overriden in the sub script.
PS: I know I could rename the variable in the subscript, but in a larger scope with centralized scripts, it would be hard to ensure uniqueness of variable names.
PPS: the real world scenario where I need directory path of current script is to load a custom module from a c# assembly. The assembly is located in a subdirectory of a loader script.
PPPS (!) : I have to stick to PS v4