tileLoaded event fired n*n times for n tiles

I trying to create 4 different tiles in 4 different elements with

var powerBITile1 = powerbi.embed(tileConatiner1, config1);

...

var powerBITile4 = powerbi.embed(tileConatiner4, config4);

After that I attached to tileLoaded event

powerBITile1.off("tileLoaded");

powerBITile1.on("tileLoaded", function (event) {  });

...

powerBITile4.off("tileLoaded");
powerBITile4.on("tileLoaded", function (event) {  });

But tileLoaded event fired 16 times! What is wrong here and how to fix it? thanks