Short answer: each self-attributing network counts every install it touched within its own windows, so the same install can be claimed by Meta, Google and TikTok at once. Your MMP picks one winner. Never add network numbers together; use the MMP for totals.
Why networks double-count installs
Self-attributing network (SAN): an ad network that decides which installs it drove and reports them itself, rather than the MMP matching a tracked click.
A user who sees a TikTok video, then clicks a Meta ad, then installs, can be counted by both. Each network is right by its own rules. Only a tool that sees every touchpoint can give the install to one source.
How much overlap is normal?
There is no fixed figure; it depends on how many users see ads on several networks. Measure your own overlap as the sum of network claims minus your MMP's paid total, and watch how it changes.
Likely causes
- Separate windows on each network. Each network applies its own click and view windows.
- Views and engaged views. Networks count installs after views that an MMP's last-click rule gives to a later click.
- MMP deduplication. TikTok's help centre describes MMPs as mostly using last click and de-duplicating across networks, while TikTok self-attributes within its own window.
- Google only sees Google. Google says Google Ads only reports conversions where there were Google Ads interactions, so it has no view of other networks.
How to confirm it
- Add up installs reported by each network for one week.
- Compare the sum with your MMP's paid installs for the same week, on the same date basis.
- Look up a sample of installs in your MMP and list touchpoints from more than one network.
- Check each network's click and view windows.
How to fix it
- Use the MMP as the source of truth for cross-network totals and budget splits.
- Use each network's own figures only for optimisation inside that network.
- Align windows across networks where you can, so overlap is easier to read.
- Report the overlap explicitly instead of treating it as an error.
| Source | Counts installs touched by | Gives each install to |
|---|---|---|
| Meta | Meta only | Meta, if inside its window |
| Google Ads | Google only | Google, if inside its window |
| TikTok | TikTok only | TikTok, if inside its window |
| MMP | Every connected source | One winner |
The self-attributing networks guide explains claims in detail, and which number to trust covers how to report both views. The TikTok troubleshooter includes the overlap check.