They manipulate their research data, but when external examiners come to their laboratories, they pretend as though they are doing everything on the up and up, but they were actually covering up their wrong doings.
この場合、次のような言い方ができますよ。
ーThey manipulate their research data, but when external examiners come to their laboratories, they pretend as though they are doing everything on the up and up, but they are actually covering up their wrong doings.
「彼らは研究データを改ざんしているが、外部の調査員が研究室に来るときは、本当は不正を隠蔽しているのに全て公正にやっているように装っている」
to manipulate one's research data で「研究データを改ざんする」
on the up and up で「正直な・公正な」
ご参考まで！
カナダ 
