Update - sometimes we ran into issues with the process described below. Since those times, GoodData has an app in their "labs" that makes the process much more straightforward. Here's the way to go about it:

A. Cloning the GD project

1. While logged into GoodData, take the PiD of your project that you wish to clone (wherever in the project you are, the PiD is the long mesh string of characters following the /projects/ in the URL (showed here in blue): https://secure.gooddata.com/#s=/gdc/projects/aiovuzysomethinggq9fhnywrlmtry|projectDashboardPage|/gdc/md/aiovuzyyrwqo28qq01gq9fhnywrlmtry/obj/490510|9152db3ddb0d - just copy it.
2. Go to https://secure.gooddata.com/labs/apps/clone_project/index.html#/clone-project
3. Follow the instructions there
4. Once the process completes, click on the link you'll get on the bottom of the page into the new project, you will need its PiD in turn.

B. Setting up GoodData Writer in KBC

1. Create a new GoodData writer
2. Select the "Use existing project" option
3. Enter your admin credentials (the same user that you used when cloning)

That's it!

Original post by tomas.ferko@keboola.com (still valid option!)

A. Cloning a GD project

1. First you need to log-in to GD and enter the project you want to clone.

2. Once you have opened the project you need to enter the so-called “grey pages” layer of GD. You do it by editing the url of the project you have entered.

The mask for entering “grey pages” is following:

https://na1.secure.gooddata.com/gdc/md/<project id>

The project id is the string of characters that usually follows the string “/#s=/gdc/projects/“

but is preceeding the string “|projectDashboardPage|“.

If you have done this step correctly you should see this screen in your web browser now.

3. Click on “Maintenance”

4. And then “Export”

5. Select the appropriate checkboxes according to what exactly you wish to clone. “include data” copies the data that is already loaded in the project, “include users” clones the user with their permissions and roles and sends them an invite to the cloned project.

Then click “Submit”.

6. Now GD starts to export the project. You have to wait until the process is over.

GD has now generated an export token you need to save for later use.

7. When clicking the url the status should be “RUNNING”. Once it's done it should display the string “OK”

8. Now create a new Writer in KBC in order to create a new blank GD project.

9. Once finished. Enter the new blank project in GD and enter grey-pager based on the steps 2 and 3.

10. Click on “import” and then enter the export token from step 7 and click “Submit” .

GD now starts copying all the data, reports and settings into the new empty project.

B. Cloning the writer settings in KBC

11. We will now clone the writer settings. Enter the KBC Storage API and find the “sys.c-wr” bucket for the writer you want to clone. The settings bucket usually contains the following tables:

12. The table names are pretty much self-explanatory. The essential ones though are “data_sets” and “date_dimensions”. Click on the tables and export them to .csv-s by clicking on “Actions” and then “Export”.

13. Now load the exported .csv tables into the new writer “sys.c-wr”  bucket that was automatically created with the writer for your cloned project in step 8.

IMPORTANT NOTE:

If you're uploading or overwriting data in the cloned project you need to make sure the KBC has it's user permissions set to "Admin" in GD's "Project and Users". It might not be the case even if it's cloned as there might be two of them one missing the correct permissions.