function Select-UniqueServerPackages {
<#
.SYNOPSIS
    Given a list of package lists (ie per server), this function returns the unique packages from each list of packages.
    If there is a higher version of a package in one package list than another, the higher version is preferred.

.PARAMETER PackagesArray
    Array of packages to process
#>
    [CmdletBinding()]
    param (
        [array]$PackagesArray
    )

    if (Test-IsCollectionNullOrEmpty $PackagesArray) {
        Write-Verbose "Array was null."
        return $null
    }

    if ($PackagesArray.Count -eq 1) {
        Write-Verbose "Only one value in array. Returning it."
        return $PackagesArray[0]
    }

    # Determine the combined unique list of packages.
    Write-Verbose "Looping through packages..."
    $uniquePackages = @{ }
    foreach ($packages in $PackagesArray) {
        if ($null -eq $packages) {
            continue
        }
        foreach ($package in $packages) {
            $name = $package.Name.ToLower()
            if (!($uniquePackages.ContainsKey($name))) {
                # If this package is not in the unique package list, add it!
                Write-Verbose "Found a package: $package"
                $uniquePackages[$name] = $package
            } elseif ($package.Version -gt $uniquePackages[$name].Version) {
                # Otherwise if the version of the package on this server is greater than what is stored, prefer the higher version.
                Write-Verbose "Found a package again! $package"
                $uniquePackages[$name] = $package
            }
        }
    }

    Write-Verbose "Returning unique values."
    return $uniquePackages.Values
}