copy key/value from more than 1 object produces more than one copy of it in the clipboard

[marc_marc]

What steps will reproduce the problem?

1. select 2 objets with one identical key/value (for exemple addr:street=A)
2. right click, copy 2 selected keys/values
3. disply clipboard or paste it into find textbox

What is the expected result?

only one addr:street=A in the clipboard

What happens instead?

it have addr:street=A addr:street=A twice)

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

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-02-01 01:10:57 +0100 (Sat, 01 Feb 2020)
Build-Date:2020-02-01 00:12:46
Revision:15806
Relative:URL: ^/trunk

Identification: JOSM/1.5 (15806 fr) Linux CentOS Linux 7 (Core)
Memory Usage: 968 MB / 1820 MB (154 MB allocated, but free)
Java version: 1.8.0_242-b08, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900
Maximum Screen Size: 1600x900
Java package: java-1.8.0-openjdk:x86_64-1.8.0.242.b08
WebStart package: icedtea-web:x86_64-1.7.1
VM arguments: [-Dicedtea-web.bin.name=javaws.itweb, -Dicedtea-web.bin.location=/usr/bin/javaws.itweb]
Dataset consistency test: No problems found

Plugins:
+ apache-commons (35092)
+ areaselector (359)
+ austriaaddresshelper (57)
+ cadastre-fr (35308)
+ conflation (0.6.4)
+ continuosDownload (91)
+ ejml (35122)
+ geotools (35169)
+ jaxb (35092)
+ jts (35122)
+ log4j (35092)
+ opendata (35313)
+ pt_assistant (34678)
+ reverter (35313)
+ scripting (30796)
+ todo (30306)
+ utilsplugin2 (35248)
+ wikipedia (1.1.3)

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1

Last errors/warnings:

[simon04]

In 15813/josm:

fix #18663 - AbstractCopyAction: copy distinct keys

Regression of r15717.