fix #292393 : Pasting tremolo between dotted notes leads to wrong rhythm

[AntonioBL]

Resolves: https://musescore.org/en/node/292393

Pasting of two-note tremolos was accidentally broken by commit 4c6f877 since their actual duration and duration type are different.
This PR adds a correction factor so that two-note tremolo pasting is not considered as a partial note paste.

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