plugins are grayed out when they don't make sense on the context, track or bus you're trying to add/insert into.
for example, plugins that have no audio ins/outs (cf. Audio column = 0:0) will be always grayed out; plugins with only MIDI i/o will get grayed out on audio tracks or buses;
otoh. on your screenshot i see duplicate plugin names (eg. "AMS Amp") but there are indeed NOT duplicates as in fact they have distinct identifiers (cf. Path, which for LV2 plugins is the called URI); they're grayed out due to one of the rules said above, NOT because they have duplicate names.
plugins are grayed out when they don't make sense on the context, track or bus you're trying to add/insert into.
for example, plugins that have no audio ins/outs (cf. Audio column = 0:0) will be always grayed out; plugins with only MIDI i/o will get grayed out on audio tracks or buses;
otoh. on your screenshot i see duplicate plugin names (eg. "AMS Amp") but there are indeed NOT duplicates as in fact they have distinct identifiers (cf. Path, which for LV2 plugins is the called URI); they're grayed out due to one of the rules said above, NOT because they have duplicate names.
hth.
cheers