Logic Masters Deutschland e.V.

This puzzle celebrates the versatility and fascination of doubling cells in combination with common rule variations and I'm very happy with how it turned out.
I have a lot of fun devising and constructing the puzzles for this series. I hope this fun can also be felt while solving the puzzles.
The puzzle brings all 5 variants that I have combined with doubling cells in previous puzzles together to a firework of interaction.
As a special gimmick, I also built a hidden doubling cell into the puzzle. On the one hand, it's a tribute to the first and so far only puzzle in the series with hidden duplication cells "Doubles Hidden Inside Squares", which is my personal favorite, and on the other hand, it's an outlook, as the subject of "hidden doubling cells" will be increasingly taken up in future puzzles.

Links to the other puzzles in the series are below the rule section.

Sudoku on:
f-puzzles
(Deactivate "Highlight Conflicts" in the "Settings")
CTC-App

Rules:

Sudoku: Fill every row, column and 3x3 box with the digits 1-9.

Double Trouble: Digits in cells marked with a blue diamond have the double value for all constraints (arrow, killer, thermo, skycraper, XV).

Hidden Double: In addition there is exactly one more doubling cell in the grid that has to be determined by the solver.

Constraints (detailed description, if needed, at the bottom of the page) : Including the doubling cells defined by the above rules, the standard rules for the constraints arrow, killer, thermo, skyscraper, and XV apply. The XV rules have been expanded to include the clues XV for a total of 15 and XX for a total of 20 and not all possible clues are given.
The rule of non-repetition of digits in killer cages refers to the actual digits (i.e. a cage could contain a 4 and a doubled 2, but not a 4 and a doubled 4).

Have fun solving!

The Double Trouble series:
It's a simple idea. Treat a few cells as if they are double their value. But it has tons of interesting logic and can turn known rule variations completely upside down. With this series I want to show this diversity.

Variant introduction: Easy to moderately difficult puzzles that show the combination of doubling cells with different variants.
Double Trouble - Arrows
Double Trouble - Killer
Double Trouble - Skyscraper
Double Trouble - XV
Double Trouble - Thermo

Easy Double Trouble: Puzzles with easy doubling cell logic.
Doubletime

Advanced Double Trouble: The puzzles in this section present more complex logic around doubling cells.
Wrecking Ball

Puzzles with hidden doubling cells: The doubling cells are not given here, but must be determined by the solver.
Doubles Hidden Inside Squares

Symmetry series: Here the basic clues form a symmetrical arrangement that provides an unique solution by specifically placed doubling cells.
The Diamonds Will Do It

I look forward to any feedback and suggestions about the series.

Constraint rules in detail:

Arrow: On arrows the digits have to sum to the digit in the connected circle and may include repeats.

Killer:
In cages digits must not be repeated and have to add up to the total given in the top left corner of a cage.

Thermometer: On thermometers the digits strictly increase starting from the bulb.

Skyscraper: Each digit represents a skyscraper of that height. A skyscraper blocks the view on all skyscraper up to the same height that stand behind it. A clue outside the grid give the number of skyscrapers seen from that direction in the corresponding row or column.

XV (extended):
Cells seperated by a V sum to 5.
Cells seperated by a X sum to 10.
Cells seperated by a XV sum to 15.
Cells seperated by a XX sum to 20.
Not all possible clues are given.