You transform your eidolon into your identical twin. Assuming you are a humanoid, the eidolon gains the humanoid trait in addition to its other traits while it's in this form, as well as any other trait related to your form (such as elf or gnome). Your eidolon gains a +4 status bonus to Deception checks to Impersonate you and can add its level to such checks even if it's untrained.
Although your eidolon looks like you, it doesn't gain any new abilities, and its statistics don't change in any way-the transformation is purely cosmetic. If this transformation reduces your eidolon's size, the eidolon loses any other effects of its larger size, such as any increase to reach. Your eidolon can still use gear only if it has the eidolon trait, which allows eidolons to use it. Any such eidolon items the eidolon was wearing change size and shape, if necessary, and its effects remain active.
You can Dismiss the spell.
Spell Effect: Summoner's Visage
Heightened (4th) The duration increases to 1 hour.
Traits
An action with this trait requires a degree of mental concentration and discipline.
You must physically manipulate an item or make gestures to use an action with this trait. Creatures without a suitable appendage can't perform actions with this trait. Manipulate actions often trigger reactions.
These effects completely transform the target into a new form. A target can't be under the effect of more than one polymorph at a time. If it comes under the effect of another, the second effect attempts to counteract the first. If it succeeds, it takes effect, and if it fails, the spell has no effect on that target. Any Strikes granted by a polymorph effect are magical. Unless otherwise stated, polymorph spells don't allow the target to take on the appearance of a specific individual creature. If you take on a battle form with a polymorph spell, the special statistics can be adjusted only by circumstance bonuses, status bonuses, and penalties. Unless otherwise noted, the battle form prevents you from casting spells, speaking, and using most manipulate actions that require hands. (If there's doubt about whether you can use an action, the GM decides.) Your gear is absorbed into you; the constant abilities of your gear still function, but you can't activate any items. You lose your Speeds and gain those of the battle form. If a polymorph effect causes you to increase in size, you must have space to expand into or the effect is disrupted.