Multipolygon margin drawn twice

[casiosmu]

What steps will reproduce the problem?

1. Downloading e.g. area 50.833 7.957 50.836 7.961 (as displayed in download map) including part of the river Sieg

What is the expected result?

The river Sieg is drawn as a way with two multipolygons as its borders.

What happens instead?

The border multipolygons are drawn twice, the second pair with an offset and not clickable (see attached screenshot). When I click at one multipolygon, it gets selected and highlighted pink, as well as the twin.

Please provide any additional information below. Attach a screenshot if possible.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2021-08-02 19:44:04 +0200 (Mon, 02 Aug 2021)
Revision:18118
Build-Date:2021-08-02 18:26:20
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (18118 de) Linux openSUSE Tumbleweed
Memory Usage: 1281 MB / 3641 MB (193 MB allocated, but free)
Java version: 11.0.12+7-suse-1.1-x8664, Oracle Corporation, OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 1920×1080 (scaling 1.00×1.00) :0.1 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: de_DE.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: de_DE
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: KDE
Java package: java-11-openjdk:x86_64-11.0.12.0
apache-commons-logging: apache-commons-logging:noarch-1.2
Dataset consistency test: No problems found

Plugins:
+ Mapillary (2.0.0-alpha.32-dirty)
+ apache-commons (35524)
+ apache-http (35589)
+ buildings_tools (35756)
+ changeset-viewer (25)
+ jna (35662)
+ notesolver (0.3.3)
+ terracer (35640)
+ undelete (35640)

Tagging presets:
+ https://raw.githubusercontent.com/yopaseopor/traffic_signs_preset_JOSM/master/DE.zip

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/Enhanced_Lane_and_Road_Attributes&zip=1
+ https://www.dropbox.com/s/qo3ai47fpv241jf/Styles_Fixme_and_Notes.zip?raw=1
- https://josm.openstreetmap.de/josmfile?page=Styles/iD&zip=1

Validator rules:
+ https://josm.openstreetmap.de/josmfile?page=Rules/GermanySpecific&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Rules/MissingWeekdays&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Rules/IndoorRules&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Rules/KeepRight&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Rules/QAToolInspiredValidations&zip=1

Last errors/warnings:
- 00188.586 E: Unsupported savable layer type: TMSLayer
- 00295.623 W: java.net.SocketTimeoutException: Read timed out. Ursache: java.net.SocketTimeoutException: Read timed out

[mdk]

The multipolygons are incomplte. The lines on the left are only the implied area filling. They don't have the dark blue line as the lines on the right.
So it's a duplicate of #21201.

[skyper]

Closed as duplicate of #21201.