The phrase "a twofold effect" is correct and usable in written English.
It can be used to describe a situation or action that has two distinct outcomes or impacts.
Example: "The new policy had a twofold effect, improving employee morale while also increasing productivity."
Alternatives: "a dual effect" or "a bifold impact".
This has had a twofold effect.
For a parent, watching these monsters has a twofold effect.
Güllner said Petry's comments about being able to shoot refugees on the border had had a twofold effect.
That fabled period, the way he talked about it, had a twofold effect on his family and friends: it laid them low financially while drawing them closer personally.
With each contraction a twofold effect is produced to facilitate the dilation, or opening, of the cervix.
Regulators hope for a twofold effect: to reduce inflation, by taking excess liquidity out of the economy, and to curb the flow of easy cash into China's securities and property markets, where some economists are warning of bubbles.
As the boys duel on a sofa, life-size silhouettes battle behind a scrim to twofold effect: thudding as a metaphor for character dynamics, impressive as a glimpse into the role of ultraviolent fantasy in the life of many adolescents.
In the realization of n-type OFET, the LUMO level lowering provides a twofold beneficial effect: firstly, an effective charge-injection can be achieved using gold or other high work function metals, and secondly, the electron transport is made less sensitive to charge trapping mechanisms related to the interaction with ambient agents such as oxygen and humidity [4].
Thus, the increase in Wnt activity associated with higher oxygen availability might have the twofold effect of increasing (a) endocrine cell mass by self replication and (b) exocrine cell mass by progenitor cell expansion [ 48].
As shown in Figure S1A, to be 95% confident of discovering at least one allele with a twofold enhancing effect, 350 kindreds must be screened.
Mutations with at least a twofold stronger effect in sex 1, relative to sex 2, account for a majority of the fitness variance in sex 1, despite a strong positive correlation of selection coefficients between the sexes.
