Duplicated attribution content

[lukemckinstry]

What happened?

Credits from Google2DImageryProvider are duplicated at some zoom levels. May have been introduced in this commit 2df3d24

Reproduction steps

1. Load sandcastle with imagery layer using per-tile/viewport dynamic attribution, eg. sandcastle loads Google Maps Satellite using the Google2DImageryProvider
2. Note duplicate content

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Sandcastle example

No response

Environment

Browser:
CesiumJS Version:
Operating System: