The License Server Administrator displays incorrect number of licenses available when there are multiple entitlements of the same feature

Description

If a feature license has been authorized multiple times using the same authorization number, the ArcGIS License Server Administrator 2019.0 may display an incorrect number of available licenses.  In addition, the client application such as ArcGIS Administrator for ArcMap or ArcGIS Pro displays the same incorrect number of available licenses.  Refer to the following image.

In the image above, notice the highlighted Desktop Standard feature. There are only three Available licenses out of five Total licenses, even when no one is using them. Use the View License Usage button to verify this.  
Because there are various factors that may cause a license to become unavailable, to determine if this bug is being encountered, try one of the following steps:

• Double-click the feature in question (for example, Desktop Standard). There should be more than one entitlement, each with a certain number of licenses authorized. The total number of licenses authorized should equal the number of licenses available.
• Stop the License Server Administrator. The number of feature licenses available should equal the total number licenses.

Steps to Reproduce

Obtain at least two authorization numbers for the same feature.  To be consistent with the example above, assume the license is for Desktop Standard.  We have EFL_1 and EFL_2. 

1. Authorize x Desktop Advanced licenses with EFL_1.
2. Authorize y Desktop Advanced licenses with EFL_2.
3. Authorize x Desktop Advanced licenses with EFL_1 again.  

At this point, you may notice the number of available licenses does not equal the total number of authorized licenses. We assume the licenses are not being consumed by a client application at the moment. If the total number of authorized licenses equals the number of available licenses, continue to authorize the entitlements again. Check to see if the available licenses are less than the total licenses after each authorization. If this happens, the bug has been  reproduced .

Note:
Although the number of available licenses is less than the total number of authorized licenses, the user can consume more than the available number of licenses, up to the total number authorized.

Workaround

• Install the ArcGIS License Manager 2019.0 License Availability Display Patch

• Upgrade to a later version of the ArcGIS License Manager