Is this a bug?

[Kagamin]

You can simply group them:

t.on!(
handlers!(
   "abc", {
     writeln("abc");
   },

   "cde", {
     writeln("cde");
   }
)
);

handlers!(
   "abc", {
     writeln("abc");
   },

   "cde", {
     writeln("cde");
   }
).bind(t);