How are you handling Google and Meta both claiming credit for the same conversion?

Running both Google Ads and Meta Ads for a client. Total reported conversions: Google says 140 for the month, Meta says 95. Backend (Shopify) shows 160 actual orders.

So the platforms are claiming 235 combined conversions for 160 actual purchases. That's a 47% inflation. Both platforms are using their own attribution windows and both are claiming assists that don't exist.

I know this is a known problem. But the client is asking why the "total ROAS" across both platforms looks so much better than the actual business results.

How do you explain this to clients without making it sound like the platforms are lying (even though kind of they are)? And what's your method for actually evaluating true channel contribution when both channels are running simultaneously?

Currently using the blended approach (total revenue / total spend) but it doesn't give channel-level insight.

yeah this is just normal attribution overlap tbh, I usually show Shopify as source of truth + explain Meta/Google are both taking credit for same users unless you run a proper dedup setup (GA4 + server-side + UTMs), otherwise you just look at blended ROAS not platform ROAS.

Get rid of Both of the networks.... Stop using them

Yeah this is just normal attribution overlap ,both platforms are crediting the same purchase, not creating extra ones.

I usually explain it like: “Google + Meta are both reporting influence, not unique sales,” then we only trust Shopify as source of truth and use platform data for direction, not totals.

For actual split, I look at incrementality (holdouts / geo tests) or just run blended MER and judge which channel is more efficient under the same total revenue, not claimed ROAS.

Classic attribution overlap, trust Shopify as source of truth and use MER for total ROAS, both platforms just end up double claiming conversions.

just tell client they both assisted in the sale and use triple whale or simple ga4 utm tracking to see the real first/last touch attribution.

Pretty normal, I tell clients platform attribution shows influence not actual sales, and I use Shopify plus GA4 data as the source of truth for reporting.

i tell clients platform numbers show who influenced the sale, not unique orders, so i use Shopify/blended revenue as source of truth and treat Google/Meta attribution as directional not exact

Yeah this is normal when running Google and Meta together both platforms use different attribution windows so they often claim the same sale. I just treat Shopify as the real source of truth and use Google and Meta data only to understand what influenced the purchase not to add them together.