Both frei0r_selector and chroma key are called "chroma_key" (fixed code included)
This bug is easy to fix (so I have included the fixed code). Go to "frei0r_selector.xml" , and rename the effect title from "chroma-key" to "Chroma Key: Advanced". Then go to chroma.xml and change effect title from "chroma key" to "Chroma Key: Basic". Note: in the fixed code below, I have added some extra changes to make the effects easier to use.
I tried to open a pull request, but I am getting this error when using WebIDE : https://gitlab.com/gitlab-org/gitlab/issues/27967
and when I try and edit the file by clicking "edit", and try to commit, a red box with no text appears and the commit fails.
So here is the fixed code for "chroma.xml" (NOTE: This code fixes another bug where the default value for the chroma key variance was 1000. I made "default='0.15'" so now the default should be 150)
<!DOCTYPE kpartgui>
<effect tag="chroma" id="chroma">
<name>Chroma Key: Basic</name>
<description>Make selected color transparent</description>
<author>Charles Yates</author>
<parameter type="color" name="key" default="0x0000ffff">
<name>Color key</name>
</parameter>
<parameter type="constant" name="variance" max="1000" min="0" factor="1000" default="0.15">
<name>Variance</name>
</parameter>
</effect>And here is the fixed code for "frei0r_selector.xml" (NOTE: many parts of this effect have been renamed for easier use. I think renaming the tag renames the option, but it still works if the "name=xyz" is not changed.)
<!DOCTYPE kpartgui>
<group>
<effect LC_NUMERIC="C" tag="frei0r.select0r" id="frei0r.select0r">
<name>Chroma Key: Advanced (Color Selection)</name>
<description>Chroma Key with more advanced options (e.g. different color models). Use if basic chroma key is not working effectively.</description>
<author>Marko Cebokli</author>
<parameter type="color" name="Color to select" default="0x00ff00ff">
<name>Color to select</name>
</parameter>
<parameter type="bool" name="Invert selection" default="1">
<name>Invert selection</name>
</parameter>
<parameter type="animated" name="Delta R / A / Hue" default="0.2" min="0" max="1000" factor="1000">
<name>Red / Hue Delta</name>
</parameter>
<parameter type="animated" name="Delta G / B / Chroma" default="0.2" min="0" max="1000" factor="1000">
<name>Green / Chroma Delta</name>
</parameter>
<parameter type="animated" name="Delta B / I / I" default="0.2" min="0" max="1000" factor="1000">
<name>Blue / Intensity Delta</name>
</parameter>
<parameter type="list" name="Selection subspace" default="0.0" paramlist="0.0;0.5;1.0">
<paramlistdisplay>RGB,ABI,HCI</paramlistdisplay>
<name>Color Model</name>
</parameter>
<parameter type="list" name="Subspace shape" default="0.5" paramlist="0.0;0.5;1.0">
<paramlistdisplay>Box,Ellipsoid,Diamond</paramlistdisplay>
<name>Shape</name>
</parameter>
<parameter type="list" name="Edge mode" default="0.0" paramlist="0.0;0.35;0.60;1.0">
<paramlistdisplay>Hard,Fat,Normal,Skinny</paramlistdisplay>
<name>Edge mode</name>
</parameter>
<parameter type="list" name="Operation" default="0.5" paramlist="0.0;0.3;0.5;0.7;1.0">
<paramlistdisplay>Write on clear,Max,Min,Add,Subtract</paramlistdisplay>
<name>Operation</name>
</parameter>
</effect>
<effect LC_NUMERIC="C" tag="frei0r.select0r" id="frei0r.select0r" version="0.4">
<name>Chroma Key: Advanced (Color Selection)</name>
<description>Chroma Key with more advanced options (e.g. different color models). Use if basic chroma key is not working effectively.</description>
<author>Marko Cebokli</author>
<parameter type="color" name="Color to select" default="0x00ff00ff">
<name>Color to select</name>
</parameter>
<parameter type="bool" name="Invert selection" default="1">
<name>Invert selection</name>
</parameter>
<parameter type="list" name="Selection subspace" default="0.0" paramlist="0.0;0.5;1.0">
<paramlistdisplay>RGB,ABI,HCI</paramlistdisplay>
<name>Color Model</name>
</parameter>
<parameter type="list" name="Subspace shape" default="0.5" paramlist="0.0;0.5;1.0">
<paramlistdisplay>Box,Ellipsoid,Diamond</paramlistdisplay>
<name>Shape</name>
</parameter>
<parameter type="list" name="Edge mode" default="0.9" paramlist="0.0;0.35;0.60;0.7;0.9">
<paramlistdisplay>Hard,Fat,Normal,Skinny,Slope</paramlistdisplay>
<name>Edge mode</name>
</parameter>
<parameter type="animated" name="Delta R / A / Hue" default="0.2" min="0" max="1000" factor="1000">
<name>Red / Hue Delta</name>
</parameter>
<parameter type="animated" name="Delta G / B / Chroma" default="0.2" min="0" max="1000" factor="1000">
<name>Green / Chroma Delta</name>
</parameter>
<parameter type="animated" name="Delta B / I / I" default="0.2" min="0" max="1000" factor="1000">
<name>Blue / Intensity Delta</name>
</parameter>
<parameter type="animated" name="Slope" default="0" min="0" max="1000" factor="1000">
<name>Soften</name>
</parameter>
<parameter type="list" name="Operation" default="0.5" paramlist="0.0;0.3;0.5;0.7;1.0">
<paramlistdisplay>Write on clear,Max,Min,Add,Subtract</paramlistdisplay>
<name>Operation</name>
</parameter>
</effect>
</group>NOTE: I have added many name changes that make this advanced chroma key easier to use.