Sure there are many similar Designs, for Example the Front Hair Part of Rainbow is maybe the most reused Part in the Show (used on Ponys like Big Mac or Lyra).
But here we have 3 Similaritys.
First the Hairstyle, who are not used on other Ponys as I know.
Lemon is a Canterlot Pony as I know, who usual have very unique Looks.
Second are the Glasses with a similar Shape, just the Color, Bridge and the Sides are different.
Third, both wear a Pearl Necklace in identical Design, just the one of Lemon has bigger Pearls.
Lauren Faust has use older Generations as Inspiration too, like the Character of Rainbow Dash from G3, who are reused in G4 for Rarity.
Maybe the Designer of the G5 Ponys have use G4 Ponys as Inspiration, like Imalou has use Scootaloo and Pinkie Pie for her Designs of Sunny and Izzy.
The show has been on for nine seasons and populated everything from castles to cities to Wild West towns. Surely in all of that some pony has to look like some other pony. Even in a whole new G. It doesn’t even have to be intentional.
But here we have 3 Similaritys.
First the Hairstyle, who are not used on other Ponys as I know.
Lemon is a Canterlot Pony as I know, who usual have very unique Looks.
Second are the Glasses with a similar Shape, just the Color, Bridge and the Sides are different.
Third, both wear a Pearl Necklace in identical Design, just the one of Lemon has bigger Pearls.
Maybe the Designer of the G5 Ponys have use G4 Ponys as Inspiration, like Imalou has use Scootaloo and Pinkie Pie for her Designs of Sunny and Izzy.